1 edit | looking for SIP provider which handles well delayed ACK msg I'm using a SIP softphone with an option of delaying the ACK messages for the call connect (200 OK), for enabling session progress media flow.
As commented near that option, this feature may not works with all SIP providers. I've tested it using 3 SIP providers but so far no success.
When I activate this option and call in, I see the 183 progress response is sent while softphone is 'ringing' - but when I accept the call an OK200 response always follows immidiately, not delayed.
Please advise any SIP providers you know which properly handle delayed ACK messages (apart from Asterisk etc.)? |
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| Re: looking for SIP provider which handles well delayed AC said by dangmoo:I'm using a SIP softphone with an option of delaying the ACK messages for the call connect (200 OK), for enabling session progress media flow. I don't understand what you are asking. On an incoming call to your softphone or other device, it's you that sends the 183, and later a 200. The provider is the one sending an ACK.
If you want the initial part of a call (e.g. interaction with your IVR) to take place in "early media", i.e. without indicating that the call has been "answered", then your system should send a 183 when the IVR starts, then send 200 when the call is transferred to a human.
1-800-426-7378 is an example of a system that works that way.
IMO, delaying ACK is not the right way to do anything, except perhaps for testing or educational purposes.
A problem with early media is that the caller's carrier may not support it (Google Voice is one example), so some users may not have access to your system at all. |
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2 edits | said by Stewart:I don't understand what you are asking. On an incoming call to your softphone or other device, it's you that sends the 183, and later a 200. The provider is the one sending an ACK.
The program seems to have its way/workaround to affect delayed ACK. Don't have an idea how they do that.
Attached a screenshot |
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nitzanPremium,VIP
join:2008-02-27
kudos:2 | reply to dangmoo
Re: looking for SIP provider which handles well delayed ACK msg What are you trying to do? cheat the operator into making the calls seem shorter??? if the call is answered all providers will give OK because guess what - the call has been answered and you should be billed! |
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| What I'm trying to do is host some short voice prompts at that softphone, to be played in session progress when some conditions are met. There are such options in that program.
I've already got a server for my website, so I'm exploring the option to run that softphone on the same server. Sounds better to me than running an Asterisk box only for some simple tasks.
Personally I don't like softphones much, and won't sit all day near softphones waiting for people to call me for free 
I'm not the one who coded that softphone, and I know the way it's described at the provided screenshot is controversial. (That's exactly why I haven't published it's name here, in this context).
However my question is focused on the technical aspect and lets keep this thread in this spirit, and leave the 'cheating' matters for cheaters. |
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nitzanPremium,VIP
join:2008-02-27
kudos:2 | I don't know about softphones, but if you run something like Asterisk as long as you don't Answer() the call, your server won't send an OK and the call won't be "answered" and you should be able to pass short messages via early media. You don't need a special carrier to support this - many already do. |
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| Thanks but as I said at the beginning, Asterisk is not an option. Just need a SIP provider which handles properly the delayed ACK . All the rest is ready from there |
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| reply to dangmoo
IMHO, your softphone simply has a bug. It should delay sending the 200, but it doesn't.
Another possibility is that it's trying to be robust, and is sending 200, because it did not receive RTP packets within a reasonable time after sending 183. You can easily check with Wireshark whether that is the case. |
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| I played a bit with the softphone. The "Delay ACK ..." feature appears to only apply to outgoing calls, and delays sending ACK when 200 is received.
The "Start media ..." option sends 183 (instead of 180) when an INVITE is received, but no RTP is sent. Possibly, it would send RTP if some came in, but that would require both a provider that does not proxy media, and port forwarding for the RTP port range. Even then, it would be strange for the caller to start hearing you without your acknowledging the call. When you press Answer, it sends a 200. IMO, there should be a separate button (or script action) to enable early media audio, but the sparse documentation shows no evidence of such an option.
IMO, you should contact the publisher for an explanation of how to use this feature, or find another approach. |
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2 edits | Hi Stewart,
I've gone ahead and contacted publishers, that's what they wrote back:
Hello,
Thank you for your interest in our softphone.
Unfortunately we cannot provide support regarding this issue and we also haven’t tested it for a long time.
When we added this feature it was working with openSIPS and Asterisk servers.
In short it was working by delaying the ACK messages for the call connect (200 OK).
Some server will wait for the ACK to begin the billing but the media is established on connect.
Best Regards
Hope I did everything right, and that setup doesn't require an additional setting (from the many available as you could see) to be ticked at sofphone end.
Notice when that option is activated, the softphone rings silently only with visual indication. This should have something to do with desired effect.
BTW one of the SIP providers I tested was Sipsorcey (which doesn't proxy media) but haven't tried the port forwarding part.
My VOIP skills are average and don't meet yours, so if reading publisher's reply makes you think of (or test) another idea on how to get it work, please advise,
and thank you for trying |
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| If you're looking for a way to provide custom audio media then another option you've got is to check out anveo.com. They have an early media control in their call flow builder that allows you to upload your own audio files and have them play back as early media.
I'm not sure that's exactly what you're after but it's the closest I can think of. |
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3 edits | said by sipsorcery:If you're looking for a way to provide custom audio media then another option you've got is to check out anveo.com.
I've tried them.
IMHO Anveo may be a good deal for complete applications hosting (for the non-techies, who wish to bypass languages learning curve).
As explained since I only need to host several short early media prompts (5-10 sec max each) and MOH files, it's not the best deal for this goal as they charge incoming calls per full minute (free account=40 daily minutes , cheapest account=60 minutes) and we handle more than 100 calls per day, a number which may grow.
If they reduced charging intervals for incoming calls it would be an option.
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