What soft phone to port?

I am going to fully port a sip client (besides the iax client I am already working on) This is a flame-free thread :) I want your input on what sip client you like, why, and in your opinion, how easy would it be to adapt to the OM platform? Take into account portability and libraries.

Re: What soft phone to port?

I personally don't care much which sip client would be ported. I would like to a sip client that could be eventually integrated with the address book, dialer, webkit (for clicking on sip links) or other apps, to some extent, in the future. I don't know how well all of the different apps