I can place a call to an extension that is behind a 2901 router from an extension behind a second 2901. The dialed extension will ring but when the handset is picked up the phone indicates that the session is still active but you cannot hear from either end what the user is saying. When placing a call to another extension behind each respective router the call can be placed and you can hear what the user is saying. There is a Dial Plan configured under VoIP with the remote IP configured using the H.323 protocol, codec g729r8 and the DTMF Relay Type is set to h245-alphanumeric. I do have 'Enable Voice Activity Detection' selected. There is no GateKeeper configured and the goal is to avoid a GateKeeper if at all possible.