Push notifications for incoming SIP calls

[jkiel]

I understand that currently a forked call to the mobile number of the
UA running sipdroid is currently the only way to get sipdroid the
receive incoming calls.

I'm wondering if it wouldn't be better to use a persistent TCP
connection to "push" notifications of incoming calls instead (see:
http://groups.google.com/group/android-developers/browse_thread/thread/4778a4e2ed9d49e1
).

I understand that this may be outside the scope of SIP, but from my
point of view and experience using sipdroid, it seems that battery
friendly mechanism other than forked calls, SMS or polling is needed
for incoming call notification.