[Asterisk-Users] BOTH UAs behind same FW/NAT

[Olle E. Johansson]

Philipp von Klitzing wrote:

>>>You will probably have to use "canreinvite=no" in the UA definitions in 
>>>the SIP.conf for those two phones..

> In your case you want the opposite: canreinvite=yes

A try to sort out these kind of opposite messages:

When asterisk connects two SIP phones, it tries to be in the middle of the media
path, to have the RTP stream go through Asterisk. This way, Asterisk may send
early media and error messages over audio.

When the call is connected, asterisk can send SIP re-invites and change the path
of the media stream, so that media flows directly between the two phones instead
of going through Asterisk. This is canreinvite=yes

In your situation, for calling between the phones, you propably don't want the
media stream to go

SIP UAC -> NAT -> Asterisk -> NAT -> SIP UAS   (canreinvite=no)
Instead
SIP UAC -> SIP UAS			      (canreinvite=yes)

However, I'm unsure if you can have a canreinvite=yes, since you may want
asterisk to be in the media path when calling outbound...

Also note that some devices does not support SIP re-invites (according to
the Asterisk handbook)

I'm a bit on thin ice here, so if I'm wrong - please, list, correct me so we
can sort this out.
/Olle