[asterisk-users] "POTS 4K linear codec"

[Cary Fitch]

I am not sure what the problems are and the reasons for the basic 64K modems
used in VOIP are.  I understand the compressed codecs that get the bandwidth
down to 20-30 K.  And perhaps the 64K units give much better potential audio
than you would get on a normal POTS line.

But, as phone circuits VOIP/SIP doesn't seem to perform as well as plane old
phones.

Multiple transcodings cause issues.  Today a cell phone or a POTS line phone
can send DTMF clearly enough to operate a credit card or other interactive
tone based system at the far end.  With SIP it is sometimes "chancy".

Is there a plain 64K codec that would simply pass through the SIP server and
be handed off to a PRI or phone co. trunk on a T1 on the other side of the
SIP server?  Digital 64K telco sounds very good as a phone conversation.

Cary Fitch