SIP to SIP Trunk Transfer causes one way audio

[RDECIT]

I've done a quick search and not found this issue, although there are a lot a one way audio problems here.

Previous instances of one way audio in the past have been caused by port blocking/firewall rules but in this case this might not be the same.

We have two sites that call each other frequently. Both have Mitel CXi II's (6.0 SP1 Release 12.0.1.24), both have SIP trunks from the same provider and both have SonicWall firewalls. There is no other link between sites, i.e VPN or other.

When a user from SITE A calls SITE B and asks to be transferred to an extension on the SITE B Mitel controller, the user at SITE A is unable to hear the person at SITE B they have been transferred to. However the user at SITE B can hear the user at SITE A but not visa-versa.

This problem does not occur in the other direction (i.e. when a user at SITE B calls SITE A and asks to be transferred to an extension on the SITE A Mitel controller there is no issue).

I'm confused with this because if the firewall was causing a issue, surely we would experience this issue with ALL calls.

 

[RDECIT]

Just to be clear "When a user from SITE A calls SITE B and asks to be transferred to an extension on the SITE B Mitel controller" The first person who answers the call at SITE B at first and initiates the transfer has no issue, only when the call is transferred does the one way audio happen.

 

[danramirez]

are you sure the two firewalls are equivalently programmed?? do you connect through a MBG or directly though your firewalls? any sip helpers or alg disabled or enabled on your firewalls?

http://www.hatkana.com

http://www.wtelecom.com

 

[LoopyLou]

As RDECIT points out the first person ( receptionist ) can hear the caller but the second can't. I would investigate that further.

You can't duct tape stupid.

 

[Billz66]

also check sip peer programming are the same on both boxes

If I never did anything I'd never done before , I'd never do anything.....