So there are 4 open source SIP phone implementations besides kphone:

* minisip: Supports full privacy via TLS.  Has its own tightly-related 
libraries.  Quite easy to port, *except* that the abstraction it uses to talk 
to the sound driver doesn't work on NetBSD.  This should be relatively easy 
to fix.

* SFLphone: This one looks pretty good from the description.  It supports 
encryption in some fashion or other.  It needs an updated libosip (trivial; 
I'd commit it myself were it not for the freeze), a port of libexosip, and a 
port of some of the "Common C++" parts -- specifically, commoncpp and ccrtp.  
This should be relatively straightforward.

* linphone: From the author of libosip and libexosip.  I don't know much about 
it.

* sipXphone: This is part of a big project based on the Pingtel source tree, 
which also includes a full SIP PBX implementation.  This is probably the 
ideal package to get running, but it needs Java for some parts.

I would dearly love it if someone would make a couple of these fit in pkgsrc.  
I can provide assistance as necessary (especially on the Java part).