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david3
join:2000-03-21

1 recommendation

david3

Member

[CallCentric] Callcentric DID Forwarding to SIP address with DNS SRV

Has anybody been successful in forwarding a Callcentric DID to a SIP address that uses DNS SRV?

I've got two asterisk servers setup with SRV records. Callcentric forwards the call to the higher priority server ok. When I stop asterisk on the higher priority server, incoming calls never make it to the secondary asterisk server, though.

I've got an ipkall DID forwarded to the same SIP address with SRV, and it works perfectly. If I take the first server down, ipkall forwards it to the second without missing a beat.

Callcentric seems to be a big supporter of DNS SRV, so it seems odd that it wouldn't work for forwarding.
VoIP2Go
join:2013-12-14

VoIP2Go

Member

That is odd. Do you have the two IP addresses also setup as A Records? Might be worth a try
david3
join:2000-03-21

david3

Member

Yes, both servers have A records assigned. Looks kind of like this:

sip1	300	A	0.0.0.0
sip2 300 A 0.0.0.0
_sip._udp.sip.mydomain.com. 300 IN SRV 10 1 5060 sip1.mydomain.com.
_sip._udp.sip.mydomain.com. 300 IN SRV 20 1 5060 sip2.mydomain.com.
Springbok
join:2002-09-13
Leander, TX

Springbok to david3

Member

to david3
Does it work if you wait 5 minutes (300 seconds) after you stopped asterisk on the higher priority server?
david3
join:2000-03-21

david3

Member

No, I tried waiting over 30 minutes after stopping it, but it didn't help.
VoIP2Go
join:2013-12-14

VoIP2Go to david3

Member

to david3
Did you replace your IP addresses with zeros so you could post here, or are they actually set at 0.0.0.0 ?

If you have the IP addresses of your servers in there then you really need to open a ticket with Callcentric.
david3
join:2000-03-21

david3

Member

Yeah, I just set it to 0.0.0.0 here as an example. The real DNS record has the server IP addresses and real domain name.

I did open a ticket with Callcentric, and they're trying to work through the problem now. They said they do support DNS SRV.
david3

david3

Member

Well, Callcentric support isn't sure why it isn't working, but they said it goes beyond the scope of their support. Oh well.

+1 for ipkall, for which it all works fine, anyway.
gweidenh
join:2002-05-18
Houston, TX

gweidenh

Member

Where are the servers located? Can you easily capture a wireshark trace at the primary server location? I would be curious to see what happens when you bring the primary server down. Do you still see Callcentric sending a request to the primary server's IP address?
david3
join:2000-03-21

david3

Member

The servers are running on two separate VPS's. With the first server down, I can't tell for sure if a request is being sent there, but that's what I suspect. I never get anything sent to the second server.
david3

david3

Member

I took asterisk down on the first server, and left it running on the second server, then I ran tcpdump on both servers while I made a test call.

Callcentric keeps sending invites over and over to the first server, receiving no response. Nothing is sent to the second server.

SRVmatter
@bezeqint.net

SRVmatter

Anon

IPKall is Asterisk server based. Asterisk to Asterisk usually works more less okay.

It's known fact, admitted many times, that CC is based on industrial switches. You wrote that you use Asterisks... this is where the problem strikes. Also, I'm not exactly sure about how DNS SRV works, but something tells me that without a regard to a server being up or down - the SRV priority value takes the place there - therefore CC always sends calls to a record with a higher priority value. Someone must take a look at a relevant RFC.

I'd advise to try to escalate this issue with CC support or Iscream.
Mango
Use DMZ and you get a kick in the dick.
Premium Member
join:2008-12-25
www.toao.net

Mango

Premium Member

From experience, Callcentric works perfectly well with Asterisk. I don't think that is the OP's problem.
Mango

Mango

Premium Member

I can confirm the behaviour reported by the OP.

~# dig +short SRV _sip._udp.test1.toao.net
10 10 5060 dslreports.com.
20 10 5060 seattle.voip.ms.
 
~# dig +short SRV _sip._udp.test2.toao.net
10 10 5060 seattle.voip.ms.
20 10 5060 dslreports.com.
 

I set up a Call Treatment with Callcentric to forward my calls to a valid SIP URI on seattle.voip.ms. test1 does not work, test2 does.

m.
david3
join:2000-03-21

david3

Member

They escalated the ticket to a manager.

They said they use asterisk for call treatments and forwarding servers, and for DNS SRV records it only uses the last record.

So it seems Callcentric doesn't fully support DNS SRV for call forwarding.
PX Eliezer1
Premium Member
join:2013-03-10
Zubrowka USA

PX Eliezer1 to Mango

Premium Member

to Mango
said by Mango:

I can confirm the behaviour reported by the OP.

I ask out of my own ignorance of this area:

Are there any security benefits to the way they are doing it?
Mango
Use DMZ and you get a kick in the dick.
Premium Member
join:2008-12-25
www.toao.net

Mango

Premium Member

said by david3:

They said they use asterisk

 
Well, well, I thought the day would never come.
said by PX Eliezer1:

Are there any security benefits to the way they are doing it?

 
»cdn.memegenerator.net/in ··· 8205.jpg

I am not aware of any security benefits. Asterisk's default behaviour is as the OP describes. As far as I know it cannot natively behave otherwise. (But like many other situations, you can write your own code that handles it to your specifications).
david3
join:2000-03-21

david3

Member

said by Mango:

I am not aware of any security benefits. Asterisk's default behaviour is as the OP describes. As far as I know it cannot natively behave otherwise. (But like many other situations, you can write your own code that handles it to your specifications).

I can't think of any, either. I'm pretty sure ipkall uses asterisk, too, and they figured out a way to make it work.