1 - Can anyone recommend a SIP to PSTN Gateway? (I'd like to connect using a T1.) Preferably Freeware on Linux. Any comments on Asterisk? I came across it, but have not really looked into it yet.
We use asterisk together with ser here and it works fine. Also the T1/E1 cards for asterisk from digium are very inexpensive. (Of course you can use any other PRI hardware supported by linux too)
It's quite easy to use and quite powerful as a PBX.
Have a look at it
Rainer