sundance-communications.com/forum Forums VOIP Phones & IP PBX VoIP & Cloud Phones, Hosted PBX, General IP Phones I'll troll with this looking for bites.

Here is the basic overview of the setup, I have a Toshiba CIX100 R5.1 with LIPU/11 IPT2020-SD all latest firmware. The service provider (********) has an ATM burstable T-1 for voice and data terminated on an Adtran TA612. The voice is brought out as POTS, then connected to a RCOU3 through Oneac C.O. line surge mods. All IPT'S are connected on the lan via an Adtran Netvanta 1335 with poe/vpn. The lan ports are set up as trunks to pass vlan 2 (native) for the data network and vlan 7 for the phones. The pc's are connected to the IPT's.

Here's the problem, I cannot obtain an acceptable volume level for both the IPT's and the caller at the same time. Pad adjustments have been made both on the phone system and the C.O. lines in the TA612. If the level is high enough for the caller to hear well enough, echo is produced on the IPT. If the level is set to not produce echo the caller cannot hear the IPT very well.

It is of my opinon that this T-1 is not compatable for this system. I have not even begun to set up for IPT anywhere through the internet yet.

Does anyone have any insight on this matter, or experienced simular situations? I would greatly appreciate any input.

My experience with the situation you have is bad or faulty echo cancellation at the POTS <--> Data gateway point(s). This means it could EITHER be caused by your Provider, the CIX, or by the Adtran. The thing to remember is echo does not exist in sip, at least not as induced echo. It may exist acoustically through bad phones, environments, or endpoints but from a SIP standpoint it is impossible. That is why you don't have echo sip to sip.

You have three potential problems: Faulty and/or ineffective echo cancellation, hot sidetone, and excessive lag in the data network. Usually when echo is induced by gain from the POTS it's not the phones causing it, at least not directly.

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