Audio loss between 2nd and 3rd members in conference

[cantr1]

I work in a call center using the Avaya One-x Agent version 2.5.60037.0 and have recently encountered an issue where an incoming call is routed to an agent that requires an interpreter. Agent places call on hold and call interpreter line then conferences in the original caller. The agent can hear both the interpreter and the original caller but the audio between the interpreter and original caller is either non-existent or at an extremely low level in one or both directions. Call recording however records both parties. Accessing the CM via SAT indicates no slip errors i.e. no 3073 errors present.
CM version R016x.03.0.141
Avaya One-x Agent version 2.5.60037.0
Problem is from a recently added VDN and the interpreter line is also an external line which is why I was checking for slips on T1s

So in a nut shell has anyone seen a similar problem and if so how did you solve it?

[mlombardi1]

Check the media resource used by the interpreter endpoint. Is it in a different network region than the agent or gateway/PN where the PRI trunk is connected? Make sure connections are defined between all involved network regions.