Please Answer for me!

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.

Just check out the above google links and the following:
http://www.voip-info.org/wiki-Asterisk+Hardware

If i don’t have V92 modem.

Can i use other modem for this?

You don’t have a V92 modem?

The x100p sucks, there are some compatible clones for this card around, they are also bad bad bad bad bad.

(most v92 modems are NOT going to work).

What you really want is a tdm card.

Zoa

In what way(s) are they bad?

falee hangups, no hangups, echo, bad caller id recognition,…

I don’t have V92 modem.

I think some modem maybe replace V92 modem.

Can I use?

I think your question’s been answered.

I think the answer is “no”!