Asterisk between phone and classic pbx

Hi guys i have a question
i have a classic pbx that support truking SIP and over the office ( another town) i want to install one or two phones.
This is a classic problem for my clients i can solve the problem with a vpn but i want another alternative and i have thinking on Aterisk
If i have an Asterisk pbx with an public and static ip, can i ad a sip trunk from classic pbx and asterisk and i can register the phone on the asterisk pbx?

sorry for my dummy question :smile:



Marco Bruni