[Asterisk-Users] TDM400P vs SIP3000 x2

[Luki]

My vote is for the Sipura as well; essentially I agree with all of
Brian's points. Those boxes work well once set up correctly. And, the
server and PSTN line doesn't even have to be close; PSTN line in
Washington, * server in Texas and a slooooow (as in 128 kbps) DSL
between them is sufficient.

There are two "issues" that I can think of:
1) as an outgoing FXO interface you do not get any call progress; the
Sipura will answer the call right away and pass down the PSTN audio;
it does not do busy detect or the like on outgoing calls. For incoming
calls you can have * when to answer the call, if at all. Call
disconnection detection and the like works quite well once tuned
(which isn't always trivial).

2) Indeed there is low audio volume on *SOME* calls. In my experience
it always occurs with the same callers, so it's somehow related with
the other end. Personally I did not find it to be an issue (the
conversation can be understood just fine) except voicemail tends to
detect silence when there is none in these cases. The recorded part is
actually fine, low volume but quite understandable.

--Luki