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IP Office, Gamma SIP (UK), Post Dial Delay (PDD)

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JoeNewton

Technical User
Jan 14, 2012
56
GB
Has anyone come across this before?

We have got a customer who has been struggling to make outbound calls intermittently for months. It has been raised with Gamma multiple times and they say that the IPO is not responding to their 200 OK messages. We have changed Internet providers, by passed the firewall, etc. etc., not luck. Avaya support kept saying they could not find a fault.

Eventually through escalation within Avaya they identified that after the IPO sends an Invite, Gamma reply with 100 Trying, but then nothing for 2 seconds; the IPO then sends another Invite, Gamma send another 100 Trying, and then after another 2 seconds the IPO tears down the call. Then after 5-9 seconds from the second Invite, Gamma send a series of 183 Session in progress messages, and then 2-4 seconds later 180 Ringing. Avaya then said it a Gamma issue and closed the ticket. I asked if these timings could be compensated for by amending timers in the IP Office, and they said no.

I fed this back to Gamma, however they say that up to 8 seconds "Post Dial Delay", or PDD, is normal, especially with mobile calls (due to poor signal, out of coverage, etc.), and to amend the PDD timer on the PBX. I said this isn't possible on the IPO, and they basically said that it is a local issue and they are closing the ticket. I have asked to speak to someone more senior at Gamma, but I feel as though I am going round in circles. I have tried to re-open the case with Avaya (I don't want to open a new one and start from scratch), but I have had no reply as yet.

So, my question is, who is right Avaya or Gamma? My instinct is Avaya, because we have dozens of IPOs on Gamma SIP with no other issues like this, and I have never changed a PDD timer, or whatever Avaya may call it.

Can anyone help? Screenshot of a Wireshark call flow attached.

Thanks!

Joe Newton
 
 https://files.engineering.com/getfile.aspx?folder=959f3536-8c46-473a-b6af-59a7194cebc7&file=Screenshot.png
Do you have a different sip trunk account with a different Gamma SBC to test with?

Thats my usual go-to with Gamma problems

Calum M
ACSS
 
We've had the same issue with multiple customers using Gamma, with different versions of Avaya firmware, and most are using Gamma connection with their router.

We have also raised this with Gamma and Avaya, Gamma blamed Avaya - Avaya blamed Gamma. (even though Gamma SIP is approved to work with Avaya)

We moved the SIP to a different provider and no more problems, therefore as far we can see the issue was with Gamma.

 
Thanks both. I will try a different account.

Joe Newton
 
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