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Unread 01-13-2010, 07:06 PM   #1
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Default One way audio but only with some PSTN numbers

Any help appreciated.
I have a consistent problem with one way audio, outbound from me is fine, but inbound to the PAP2 there is no audio received, however this problem only occurs with some Sipbroker PSTN access numbers.
I am using a PAP2 connected to a Netgear MBR624GU 3G router. The PAP2 is registered to Callcentric. Echo test works OK and I have received a inbound SIP call with good two way audio.
I am not using STUN (syslog reports that I am using a symmetrical NAT)
I have the other line of the PAP2 registered with Sipdiscount and all works well including a UK DID number which allows incming calls from the PSTN.

The problem I experience is that using Sipbrokers PSTN access numbers on the callcentric registered line for some of the numbers there is one way audio whereas for others all is OK with good 2 way audio. I do not understand how this can be as I thought that on a call from a PSTN into a Sipbroker number that Sipbroker would then just pass the call onto Callcentric.
The problem is entirely repeatable
The ones I have tried which al;ways have the one way audio (no audio inbound to the PAP2) are:
All 7 of the listed Australian numbers -(Voxbone and Pennytel)
Both Auckland (NZ) numbers - (DIDWW and Callcentric)
A Boston (USA) number -Callcentric
An Oxford (UK) number - DIDWW

Whereas the following always have good two way audio:
An Oxford (UK) number - VOIPtalk
A Manchester number - VOIPtalk
A London (UK) number - Telappliant

A theme which has emerged is that all the one way audio ones have the male greeting on connecting to the Sipbroker PSTN number whereas all the 2 way ones have a different greeting (female)
So is there some difference in the boxes being used at the Sipbroker hosts?

What I am trying to acheive is a shared DID facility reacheable from an Australian number
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