Can i achieve the following:
Build an Asterisk Server with one SIP IP phone connected inside and an
outside phone line connected to a modem, so that
Asterisk would be a PSTN gateway for that One phone?
What type of modem for PSTN gateway ?
(I think use Intel V92 data/fax/voice modem but Can I use other modem.)
Google for “asterisk+V92+X100P” and you will find that the X100P card from Digium is actually a V92 modem. To this kind of V92 modem/X100P you can connect a phone line.
So the answer to you question seems to be “yes”, but I haven’t tested this…
Also: Digium stopped selling the X100P card, but V92 modems and other X100P clones can still be bought.