Mitel 470 SIP trunk one way voice

[Wojtek]

Hello All,

I got a problem with Mitel 470 on SIP trunk, there is one way voice behaviour. Voice is going out from Mitel, but mitel do not receive external calls voice. There is an SBC connected into Mitel, and going via SBC to Provider Box. We can see traffic on traces, invite, ringing, etc. But voice is just going out of the Mitel PBX, no coming voice into it.

Any idea?

kind regards
Wojtek,

[bojo387]

My understanding is this is a public SIP trunk, If it is incoming no speech, then I'd check the SBC side first. I don't know at which segment you took your trace at but you'll need to check: Does the SBC receive RTP from provider side? And is the SBC throwing out the RTP to the LAN (internal) side? As we know, when there is IP translation involved, sometimes the wrong IP address is used on the RTP packet... so there might be some tweaking needed in the NAT or SBC function.