We have an Avaya IP PBX connected to a 3825 by 4x E1's at Site A. This is connected to an 2MB MPLS wich in turn is connected to another 3825 and a TDM PBX via 4xE1's at site B.
All calls flow from site B to site A. During a conversation from site B the users will start to have one way speech during the call and will eventually hang up. The speech is heard flowing from site B to site A. The users at site B no longer hear the users at site A.
the proble effect approximatly 20% of all calls transversing any of the E1's
Call flow below. Codec is G729 over the MPLS. We have 4x PVDM2-64's in each router.