Delay answer on PRI

[darrel]

I have a customer that has a PRI that's been working fine for years, that now is complaining that there is a delay when a call is answered. The call is answered but caller misses "Thank you for calling XYZ company".  There is 2-3 second delay. Checked for changes with the carrier none reported. They have an IP PRI that goes through an Adtran and is handed off as a TDM PRI.

Tried changing the "Setup Request Acknowledge" timer from 4 to 2 and 1 second no change.

If a call is picked up during the first ring they don't seem to get a delay

[Tech Electronics]

Darrel,

It would be doubtful that your change would make a difference if the delay only happened after the first ring.

What version of software are they on?

I have done some research on this recently as we have a customer with the same issues when receiving calls from a Hunt Group.

Thanks,

TE

[darrel]

They have 6.3.7.78

These calls do hit a hunt group. Most of the users are "Hot Desk Profiles"

I think it has something to do with the hunt group members being Hot Desk Profiles. After questioning the users, they say when the call key stops flashing the outside caller can hear them. Even though they answer the call, it doesn't connect until the Call Key goes steady.

[acejavelin]

They have 6.3.7.78

These calls do hit a hunt group. Most of the users are "Hot Desk Profiles"

I think it has something to do with the hunt group members being Hot Desk Profiles. After questioning the users, they say when the call key stops flashing the outside caller can hear them. Even though they answer the call, it doesn't connect until the Call Key goes steady.

Interesting observation... So in a PRI ISDN call, a lot of messages occur in inbound call setup...

SETUP -> Mitel
CALL PROCEEDING -> PSTN
ALERTING -> PSTN
CONNECT -> PSTN (this is where the Mitel says "someone answered the call")
CONNECT ACK -> Mitel (the carrier acknowledges that someone answered the call)
~~~Audio occurs~~~
DISCONNECT -> (whoever hangs up first)
RELEASE
RELEASE COMPLETE

The delay appears to be in the Mitel getting the CONNECT ACK from the carrier, when it does, the light on the call key should go solid.

You could confirm this using the SSH shell and monitoring a test call.

If the carrier has a Adtran or other SIP/ISDN gateway in there, my first instinct would be to reboot that device...

[Tech Electronics]

darrel,

I would upgrade them to at least 6.3 SP5 to solve the problem, and while you are at it you might as well go to the latest version of 6.3 SP7 and be done with it.

V6.3 SP4 (6.3.8.105) Released on January 14, 2020
System Administration and Diagnostics Version 6.3.99.0
Database Programming Version 6.3.8.99
MIVO-588 - Delayed audio when answering hunt group calls.
MIVO-446 - Delayed audio on 69xx sets when answering PRI trunk calls.

V6.3 SP5 (6.3.9.108) Released on July 27, 2020
System Administration and Diagnostics Version 6.3.102.0
Database Programming Version 6.3.9.102
MIVO-281 - Delays in audio when answering all ring hunt group calls. Set Spare Byte Data 4 to 16.

Thanks,

TE

[darrel]

Thanks

I'll upgrade their software.

It is an All Ring hunt group.

Did reboot the Adtran, worked with a good carrier tech I've worked with in the past.