Topic '[CallCentric] Recommended settings for 3CX can be problematic.' in forum 'VOIP Tech Chat' - dslreports.com

Re: [CallCentric] Recommended settings for 3CX can be problemati

Thu, 22 Nov 2012 00:05:24 EDT

Iscream posted : Hi Nicky, I've been contacted (via PM - this is DSLR's instant messaging) by DBOD who passed to me your message and I've already replied back to him (although the PM status shows that he's not yet read it).

I've also forwarded that message to our head of support and other execs asking them to reply directly to you (and to DBOD).

Our head of support is in charge of doing interop testing with your software (he's doing it many years already with all vendors; he was the one who performed original testing - when your Callcentric template was created).

On another hand - I'm also always against of when software debugging and troubleshooting is brought to those boards in attempt to do it publicly [by probably hoping that a public pressure at vendor{s} in question may speed up the process - this is one small "negative" aspect of those boards' functioning, but there are many positive ones causing myself to frequently participate here] instead of contacting vendors in charge and letting them resolve the issue.

On 3rd hand :-)) I may tell that there were no changes in how Callcentric "servers" operate - your existing template works perfectly there, where DN "A" record resolution and plain "callcentric.com" domain is used, but the issues reported are related to DN SRV resolution with additional domain name introduced recently - "srv.callcentric.com" where your software works when all weights are all zeros (while always sticking to the first record resolved), but when weights are NON ZERO - the software behaves the way as DBOD posted above . Please note - the weights were always of all the same value (30) while 3CX software was sending REGISTER request to one resolved record, then was getting a 407 "authentication required" reply from our SBC, but then it was attempting another DN resolution - then sending its following Register request to _another_ SBC instead of staying in "dialog" and sending the reply to the same one which was used originally... That's the issue there as described by DBOD.

Please, create an account with DSLRs - then you'll be able to PM to me directly while I'll be able to do the same - I believe that will improve the effectiveness of the conversation :-))

Thanks for knocking in and welcome to this forum.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 21 Nov 2012 23:00:21 EDT

anon posted : Can someone from Call centric contact me and explain to me what the problem is? This is a long thread and contains many attempts.

nb@3cx.com

Best thing to do is to send me a new account with new credentials and we will conduct a test to see.

Also if a change was made in callcentric servers, then of course the 3CX template must be updated and rechecked and callcentric must now be retested again against the latest version of 3CX and callcentric. Lets start on that first before blaming DNS resolution problems in 3CX...

Now I have checked the srv records of callcentric and they have the same weight.

Reading 3CX sources I see that if all weights in SRV response are 0 - 3CX selects first record always, otherwise it selects random record with probability corresponidng to weight (ie. if you have two records, first has weight 80 and second has weight 20 - than it selects first with probability 80%, or second with probability 20%).

This is correct behavior.
So I am not exactly sure what / where the problem is.

Also in my opinion, we should delete this post and come up with a document that works across all platforms - Just like we have with all the other providers we support. Because this post is full or trial and errors.

3CX Phone system has a configuration template in the installation which is selectable and should populate all options automatically. Options that at the time that the introp was made between 3CX and Callcentric, both callcentric and 3CX had approved. All these options were working with callcentric until Mid October / beginning of November.

Now of course, if things have changed, we need to retest this. To be honest, we have not attempted to retest with callcentric after the problems that occurred during the past month.

Let me know how you guys with to proceed.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 21 Nov 2012 22:07:51 EDT

Iscream posted : I've replied to your PM. Please check yours :-))

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 21 Nov 2012 16:32:35 EDT

DBOD posted : Iscream, Check your IM. 3CX has expressed an interest in the non-zero weight SRV problem.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 18:47:41 EDT

DBOD posted : True, I think it is odd that they are not aware of the issue from other avenues. 3CX has a lot of users. I wouldn't think this is the first voip provider to implement SRV records that brings 3CX down. Maybe Callcentric is ahead of the curve? It is not an imminent problem at this point but it does hamper a voip provider's strategy if it is indeed a 3CX issue. At this point 3CX is not acknowledging a problem. Hope they can resolve it soon. I'd feel better if Callcentric implemented a more robust SRV system and 3CX could follow it.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 18:32:57 EDT

PX Eliezer posted :

said by DBOD:

From the 3CX response you get the impression that callcentric and 3CX haven't been talking.

That's a possibility, but another possibility is that 3CX is big enough such that the left hand may not know what the right hand is doing....

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 15:01:36 EDT

DBOD posted : I just lost registration on the bypass domain. Going back to what is working for now. I am going to run the condition that fails to process the weighted SRVs send the wireshark logs to 3CX

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:58:39 EDT

DBOD posted : From the 3CX response you get the impression that callcentric and 3CX haven't been talking.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:57:37 EDT

DBOD posted : Here is the 3CX response on the general forum

Hi - thanks for the detailed explanation. We are not aware of this issue.
Probably if something has changed in call centric, we need to be updated in order to make the changes to the template.
3CX DNS resolution also changes in case it is a registration based authentication account or a non registration based trunk.
This is interesting.

"pulls the DNS A record for the second random server and sends the REGISTER response with the first nonce to the second server instead of the first server that issued the 407. Needless to say the registration never completes. "

What server are you using and what outbound proxy do you have specified in the account configuration?
Is it a registration based provider or a trunk?
Can you make a wireshark capture and send this to ...

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:54:54 EDT

VexorgTR posted : Thanks DBOD for looking into this... I have not the time to do so.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:52:39 EDT

DBOD posted : Finally today they have looked at my concern in the user forum and are request wirehark logs. I'll sign on srv.callcentric.com and give it to them.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:48:47 EDT

DBOD posted : I can't ask 3CX since I don't pay for support. They are ignoring my query in the user forums.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:41:12 EDT

Iscream posted : We've stopped announcing "bypass0." as of this moment.
Thanks a lot for your time testing!

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:39:19 EDT

Iscream posted : That's the question to 3CX, not us.

We're just a messenger (providing SRV records) :-))

I'll ask our techs whether they have this issue on control with 3CX guys.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:22:18 EDT

DBOD posted : Any estimated time for the 3CX SRV fix?

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:16:39 EDT

DBOD posted : I am getting off the bypass0. Will leave one running on bypass. Don't see much value or harm in it for now.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 14:02:48 EDT

Iscream posted : Ouch, you've caught me here (thanks to your log!). I tried to create this test bed for you, to check 3CX's stickiness to particular SBC, last night, while was thinking about going to my own bed :-))

The "bypass0." was created as DN SRV RR within our DN servers, but wasn't actually provisioned within SBC layer allocated to support this new domain.

Considering the fact that 3CX's "stickiness" issue was not resolved - it keeps sticking to the same SBC - I now withdraw this test setup (related to "bypass0.") completely. If you want or see any reason in continuing doing so - you may keep playing with older "bypass." (non zero weights). Thanks for your time!

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 13:52:02 EDT

DBOD posted : I make the presumption that 3CX and Callcentric can handle multiple SIP trunks from the same voip provider and the same PBX. I haven't seen any indication of a problem in that area but it may be an odd situation that you do not see often and worth mentioning. We run two business in this office with separate accounts. When I ran the other 3 tests earlier I shut off the second account just to make the logs easier to read. These three errors have occurred while both sip trunks are registered with CC but one using bypass0 and the other one just callcentric.com

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 13:47:08 EDT

DBOD posted : Well I have to say that the Network error 500 is a once in a year occurrence around here. It has now happened a second time on bypass0 this morning. I have also now another error on bypass0 that I have never seen.

14-Nov-2012 10:08:43.656 Call to T:Line:10001>>18006383120@[Dev:sip:1777XXXXXXXX@bypass0.callcentric.com] from L:373.1[Extn:606] failed, cause: Cause: 483 Too Many Hops/INVITE from 204.11.192.135:10123
14-Nov-2012 10:08:43.656 [CM503003]: Call(C:373): Call to has failed; Cause: 483 Too Many Hops/INVITE from 204.11.192.135:10123

Given that I am simultaneously running another Callcentric sip trunk through the same PBX without errors on the callcentric.com port 0 SIP server and now I have three weird errors in a short period, I would say this is not a spurious correlation. Something odd is happening with this setup. The question is what? I will let it run awhile longer. I'll take a look at the wireshark logs in a few hours and see if there are any clues in there.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 13:18:05 EDT

Iscream posted : I don't think those lines [you mentioned above] are relevant somehow to the setup in question - this is just a "regular" 500 Network Failure, could happen due to many different reasons (this event isn't good by itself, but happens - could be network connectivity issue or even something on our side which prevented the call from progressing properly).

For me it was important to see whether or not 3CX will register to different SBCs or keep sticking to the same one. Seems like the latter. Just tried to find "something" for 3CX that could cause it to move onto another SBC when it's time to re-register.

Well, seems like no luck (one of my hopes was that when only a few records returned - it may behave itself) until 3CX will actually fix their SRV related behavior.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 12:45:10 EDT

DBOD posted : I just saw this in the 3CX server activity log. It doesn't bode well. Not sure of the source of the issue yet. Will let it run for another hour.

14-Nov-2012 09:27:49.540 Call to T:Line:10001>>18003454344@[Dev:sip:1777XXXXXXX@bypass0.callcentric.com] from L:369.1[Extn:602] failed, cause: Cause: 500 Network Failure/INVITE from 204.11.192.135:10123
14-Nov-2012 09:27:49.540 [CM503003]: Call(C:369): Call to has failed; Cause: 500 Network Failure/INVITE from 204.11.192.135:10123

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 12:11:29 EDT

DBOD posted : Third test

SIP server hostname bypass0.callcentric.com
SIP server port 0
Outbound proxy hostname
Outbound proxy port 0

So far bypass0 seems to operate the same as callcentric.com SRV records. Except the list is shorter and the port is 10123. 3CX is still sticking to alpha10 but it registers and seems to stay that way. I will leave one of my accounts on bypass0 for the rest of the day and monitor it. 3CX doesn't seem to care how long the SRV list is. I was able to handle the eDNS TCP queries with the correct DNS server. Actually I think it may have even worked with truncated queries but don't quote me on that.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 11:30:10 EDT

DBOD posted : First attempt to register with bypass0 succeeded. I need to go and will check back in 40 minutes.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 11:26:53 EDT

DBOD posted : Further observations on the First test and Second test. In both situations 3CX will occasionally get registered. This happens when it responds
to the correct server after 407. My guess is that when it formulates the response it is not sending it to the send server in the ordered
list it is suppose to create from the SRV records. It is sending the response to another randomly selected server. Since the SRV list is short
I am able to see it occasionally respond to the 407 challenge to the correct server. Will test bypass0 in a little while.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 11:08:29 EDT

Iscream posted : Yeah, I actually count on "bypass0." that it may work with 3CX because it's resolved with weights "0". I want to see how 3CX behaves when there are just 3 or 4 SRV records returned.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 10:58:12 EDT

DBOD posted : First test

SIP server hostname bypass.callcentric.com
SIP server port 0
Outbound proxy hostname
Outbound proxy port 0

DNS SRV records have alpha9 thru alpha12 all priority 20 and weight 30. Alpha12 is selected 407 code is returned with the first nonce. 3CX queries
A record for Alpha10 and sends the REGISTER request response with the first nonce back to Alpha10. Wrong server! Does not register.

Second test

SIP server hostname bypass.callcentric.com
SIP server port 0
Outbound proxy hostname bypass.callcentric.com
Outbound proxy port 0

Exact same situation. Except I noticed that 3CX did get registered once because it responded to the correct server after the 407 challenge.. But lost it on the re-registration shortly there afterwards for the same reasons as above.

Will test bypass0 in the next few hours.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 04:24:24 EDT

DBOD posted : It is 1:20 AM. I am going to sleep. But I'm up for some config testing. I don't care which ports are used. I predict the non zero weighted SRV will break 3CX. I'll get back to you in about 12 hours.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Wed, 14 Nov 2012 01:57:44 EDT

Iscream posted :

said by DBOD:

This is like watching the paint dry.

For the last day I have been running my 3CX with

SIP server hostname callcentric.com
SIP server port 0
Outbound proxy hostname "field left blank"
Outbound proxy port 0

I have to report that there seems to be absolutely no difference between how it handles the DNS SRV or how reliable it is versus the following which I have been using for the last month.

SIP server hostname callcentric.com
SIP server port 0
Outbound proxy hostname callcentric.com
Outbound proxy port 0

Both have been rock solid reliable since last Wednesday night when CC made the big changes.

To DBOD:

I have one idea... Please may you make one experiment for me?

Try to configure your 3CX to use server hostname "bypass.callcentric.com" (with our without outbound proxy).

Use SIP server and OBP port 0 (our DN will return port 10123, but if that works for you - we can set other ports - it seems for some reason people tend to like port 5080 more than 10123, which looks racists to me :-)).

The "bypass.callcentric.com" SRV uses weights of "30" there.

Then you may try also using "bypass0.callcentric.com" - same as above, but SRV is configured with weights "0s" for all records.

Please let me know whether your 3CX worked with some, all or not at all with above config combinations and whether it stopped sticking to a particular SBC (chooses different SBCs at different times) - somehow I believe that if it worked for you - then it also now uses different SBCs vs. sticking to one only.

Please don't stick to this config yet - this is a part of experimental setup and may change on instant. If it works - we'll create some more persistent DN records. Thanks.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Tue, 13 Nov 2012 13:01:21 EDT

DBOD posted : This is like watching the paint dry.

For the last day I have been running my 3CX with

SIP server hostname callcentric.com
SIP server port 0
Outbound proxy hostname "field left blank"
Outbound proxy port 0

I have to report that there seems to be absolutely no difference between how it handles the DNS SRV or how reliable it is versus the following which I have been using for the last month.

SIP server hostname callcentric.com
SIP server port 0
Outbound proxy hostname callcentric.com
Outbound proxy port 0

Both have been rock solid reliable since last Wednesday night when CC made the big changes.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 14:10:09 EDT

Davesnothere posted :

said by Iscream:

The outbound proxy is not required. The way it's [un]configured differs for each particular device. Having it configured/enabled was advised for simplicity for non technical users.

Yeah, you don't need STUN either, when working with Callcentric (was a first reason for us using NAT penetrating SBCs since very beginning).

Also - we don't require a registration in order to be able to make outbound calls. If you're comfortable making calls without a dial-tone of if/when a device may be configured to provide a dial-tone without being registered - no problem on our side to accept calls.

The registration is only required in order to receive inbound calls toward your device and/or for call-treatments [based on being registered as a condition] to work.

So that's 3 things which we might not need (already did not use STUN).

Are you telling us that certain fancy (above defined as extra/optional) parts of the config for CC are more to make their service more fool/idiot proof, aka more robust ?

Would there be any point in any of us on typical ATAs to try any of the simplification changes mentioned in your most recent post ? (and just keep the SRV stuff enabled)

IIRC, a PAP2T can be set to issue a dialtone without registration, for example.

I suppose you'll say "if it works (as it is)...." ;)

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 13:57:36 EDT

Iscream posted : The outbound proxy is not required. The way it's [un]configured differs for each particular device. Having it configured/enabled was advised for simplicity for non technical users.

Yeah, you don't need STUN either, when working with Callcentric (was a first reason for us using NAT penetrating SBCs since very beginning).

Also - we don't require a registration in order to be able to make outbound calls. If you're comfortable making calls without a dial-tone of if/when a device may be configured to provide a dial-tone without being registered - no problem on our side to accept calls.

The registration is only required in order to receive inbound calls toward your device and/or for call-treatments [based on being registered as a condition] to work.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 13:34:22 EDT

DBOD posted : One more setting I have been running. I realized that stun was causing me problems in 3CX with Callcentric registration consistency. I avoided it a long time ago by going to the Voip Provider Advanced tab and setting "Which IP to use in 'Contact' field for registration" to Internal.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 13:27:39 EDT

DBOD posted : I should clarify that I am using the callcentric.com port 0 for the SIP server.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 13:26:10 EDT

DBOD posted : I'm game. Except what do they mean without outbound proxy? You can set the server field blank but it won't let you leave the port field blank. I am setting both of mine to 0. Under the advanced tab there is a "Require registration for:" that I have set for "In and outgoing calls" . I am leaving that alone.

So far it is pulling the SRV records as expected and sticking to alpha10 port 5080 as expected.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 11:49:23 EDT

Iscream posted : As a matter of fact - that's a good advice! If your side doesn't use some sort of aggressive NAT/Firewall which would be actively hunting against SIP packets - you don't need an outbound proxy while working with Callcentric.

The OBP is used/recommended just as an additional measure helping to penetrate NAT related issues.

Please try it (without OBP) - let's see how it works.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 11:26:54 EDT

VexorgTR posted : I got a message from 3CX about it.

Hi

Thanks for your email.

There is a 3CX issue at this point in time with SRV records.

Can you please try to connect to Callcentric WITHOUT using the Outbound Proxy and advise the outcome.

Thanks and regards

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 02:06:13 EDT

Iscream posted : Callcentric does have lots (and lots and lots - anybody wants to buy some lightly used SIP gear? :-) I'm really kidding, we don't sell any gear) of ATAs on shelves. Yes, we do have 3CX servers installed - our support engineers are in touch with 3CX, but that "touch" is not in a real time and doesn't happen momentarily.

Our support people are frequent lurkers on this forum - they surely read this thread too.

Tomorrow we're closed due to observing Veteran's day holiday, but at Tuesday we may hear something from or post something to, 3CX, but I'm not in charge of those conversations (I'll keep my evil eye on them though :-)).

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 01:46:44 EDT

DBOD posted : Iscream,

I remember reading in a post a while back that Callcentric had some ATAs on hand to simulate different customer problems. Does Callcentric have a 3CX PBX server to run tests on? There is a free version of the software available. Does Callcentric and 3CX collaborate on customer issues that you deem important?

Re: [CallCentric] Recommended settings for 3CX can be problemati

Mon, 12 Nov 2012 01:40:07 EDT

DBOD posted : I think you misunderstood the question. I believe there are two of you that saw the problem you have described. Your setup will not follow the the SRV RRs correctly. It doesn't even register with the first one correctly. Yes it registers but not on the port given by the SRV RR. I still don't understand why your problem occurs though.

My question was has anyone has seen 3CX following the SRVs RRs FQDN and port as it was intended on callcentric.com port 0. I don't think 3CX has a chance of doing it unless both SIP and OBP servers are set to callcentric.com port 0. Even then you have to trap the SRV RR change to see it happening. And I don't mean the round robin changes to the RRs.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 22:31:42 EDT

VexorgTR posted : There were two of us with different ISP's that saw this. If we just use the "A" record, we're ok...

It's not a nightmare, but it will be interesting to see if the 3CX crew comes up with a fix.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 22:08:29 EDT

DBOD posted : I'm not making 3CX setting recommendations. Just observations. I realize that the my supposition that 3CX will be more secure using the dumbed down callcentric.com SRV records is untested by me. What we do know is that 3CX is not working with the srv.callcentric.com SRV records. We also know that 3CX does registers just fine with the callcentric.com SRV resource records albeit it sticks to the same server independent of the order the RRs are sent in the answer to the query ( I don't think that is a standard non-compliance issue BTW because of the 0 weighting). And it only follows the RR port number if the SIP server port is 0 and probably the OBP server port is 0) What I have not actually done is witnessed this in battle. When Callcentric starts adding and dropping SBCs and changing ports, will 3CX follow properly? I hope so but given their performance with the srv.callcentric.com records it is only a hope. I'll leave my wireshark running to see if I can trap that behavior. 3CXs silence on this issue is deafening! Anybody have any connections with 3CX to get attention on this issue?

Has anyone witnessed 3CX following the RRs in the DNS answers as they are supposed to?

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 20:32:06 EDT

gweidenh posted : Sounds like VX needs to change his sip port to 0

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 19:56:38 EDT

Iscream posted : At this time we don't have immediate plans to replace 0s with non 0 weights - the consideration was only to help you and customers having their configurations like yours. Because you asked - no more needs to immediately change this behavior.

The same is about about using dynamic port hoping - in a long run I'd not recommend to use SRV mechanism to choose a name of SBC while still using some fixed port (be it 5060 or 5080) because it may happen, at some time in future, that all ports which are not _currently_ being announced, the same as all SBC names which are not being currently announced by DN SRV or A records - will be explicitly closed and blocked by our dynamic firewall (with exception of currently registered or with active calls devices). That is the whole principle of using load balancers and resource protection mechanisms to allow access only to those devices which are currently available with adequate processing power.

The mechanism outlined above is within 2-4 months down the road, may take even longer if more non-compliant devices discovered or there is a significant demand from active (read - reasonable) customers, but earlier of later this mechanism must be deployed because with the current age of Internet, its threats and ability to "hunt different service providers" just for sports - this is the only way to go; any single, the most powerful, SBC has always a finite amount of processing power therefore it always may be "suppressed" by a matching fire from malicious/zombie devices while having ability to quickly add more SBCs with dynamically changing ports - gives us an ability to remove devices from fire which were attacked _before_ their resource had been exhausted while adding another device{s} with new resources available to serve more requests.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 19:33:48 EDT

DBOD posted : By setting both SIP and Outbound Proxy servers to callcentric.com port 0 in 3CX, my registration follows the SRV RR server and port specified which is the purpose of the SRV implemention.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 19:27:50 EDT

DBOD posted : I am not having any problem registering with those settings. Are you saying it is just a re-registering problem after you have lost registration? How often are you losing registration? Can you simulate it without having to wait for the problem?

Here is my concern with your set up. And I think we get into trouble here because CC isn't fully aware of the defects in 3CX.

With the setup you describe, 3CX is pulling the SRV records from callcentric.com and as we know it is defaulting to alpha10. But it is only using the SRV record for server selection not port selection. So registration is happening on alpha10 port 5060 with your set up. I don't know how stable that is or why 3CX loses and can not reconnect under that situation. If CC loses alpha10 you should be able to get back on another server. One question I have is while callcentric can change both servers and ports in SRV records, will they still listen to 5060?

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 19:00:02 EDT

VexorgTR posted : both are callcentric.com

5060 for the sip port....

straight from CC tech support.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 18:56:12 EDT

DBOD posted : But I also want to know what are your SIP server and port settings when you are expericencing this??

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 18:44:12 EDT

VexorgTR posted : Outbound proxy hostname or IP = callcentric.com
Outbound proxy port (default is 5060) = 0

When I set it like this... In the event that it "falls off" it can't get back on by itself... 3CX just starts with this error....

01-11-2012 10:44:45.937 [CM504007]: Next attempt to register Lc:10000(@Callcentric[]) is scheduled in 120 seconds
01-11-2012 10:44:45.906 [CM504005]: Registration failed for: Lc:10000(@Callcentric[]); Cause: Cause: 408 Request Timeout/REGISTER from local

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 17:00:50 EDT

DBOD posted : I recognize that it is not literally Port 0. Designating port 0 seems to be the method of forcing 3CX to look up SRV records. Not necessarily use them or use them correctly. The 3CX administrator manual for version level 11 has no discussion of SRV records at all. So I can only deduce based on observation with wireshark what is happening.

3CX is broken when using srv.callcentric.com port 0 on both SIP and OBP servers. It is my belief that it is a 3CX problem with the non zero weights. I'd like 3CX to chime in on that issue. Please don't use non zero weights on callcentric.com to help us 3CX users. I can understand why you would choose to implement non zero weights however for all users. Non compliant user agents need to change. If you need to implement it, leave another domain with non zero weights for us problem children.

I was searching for a way to avoid problems with sticking to a particular SBC in the rare event that a automatic mechanism failed to remove the SBC.

Setting both of my server options to port 5080 forces A records but randomizes the servers. I recognize that it will still break if you decide to start port hopping. Since 3CX appears to me non-compliant, I have to pick my poison. I don't like it but I am sticking with the SRV records.

Re: [CallCentric] Recommended settings for 3CX can be problemati

Sun, 11 Nov 2012 15:19:37 EDT

Iscream posted : The only reason to consider replacing "zero" weights by non zero ones for "callcentric.com" - was in an attempt to solve your problem. If you say that you prefer to stay with "0s" there - no problem, no one would ever mess with that :-))

B/w - there is no worry about 3CX server sticking to some particular SBC when weight "0" is used - the moment our system detects any issue with any SBC - it's literally milliseconds to remove (in case of complete failure or maintenance) or to change the announced SRV's weights (in case of overload); a TTL for those SRV records is set to 60 seconds thus within this interval all DN servers and/or DN resolvers will have updated SRV settings for domain in question.

Of course - mistakes do happen as well as mis-configurations, therefore it's better to have a fully operational SRV based "round-robin" setup, but until 3CX fixed their issue - it's okay to let the 3CX server to "stick" to a particular SBCs while the DN SRV records return back (resolve to) that SBC as one of "announced" addresses and until an announced weight is still "0".

Also, worth mentioning, I do hope that it's clear that whatever is called "port 0" is not actually a UDP "port 0" at all. It's simply a configuration "switch" which tells the program to get the port value from the SRV record instead of using a preconfigured one.