We have a client experiencing intermittent one-way audio behind an Adtran Netvanta series router and have tried every trick we know with the Adtrans to clear this up. Wondering if anyone else may have experienced this issue?
Our client is using a hosted phone service (broadsoft), have all Polycom VVX500's, and 650 VoIP phones, and was provided an Adtran router with 3 bonded T1's for Voice/Data.
It is a local provider and the path to the cloud is on-net for the provider, QoS appears to be working as designed.
The MOS /AER settings appear great, but intermittently around 2-3 times per day at random the operator answers a call and the caller can hear her but she cannot hear the caller. If she presses the hold button, and un-hold they have 2 way audio. That leads me to think it's somehow NAT related, we have disabled the normal SIP ALG services and it is still happening. I am much more familiar with Cisco CLI, it appears I must have the IP firewall command enabled for NAT to function, but am not sure if I am missing something or what.
Obviously other clients with a similar setup are not having this issue.
There are a couple beers in it for whomever knows the answer.
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