[asterisk-users] Force a SIP friend to use a certain IP?

[Adam Moffett]

Suppose I have two IP aliases on one asterisk box.

I have to talk to SIP friend "A" using IP x.x.x.x and I have to talk to 
SIP friend  "B" using IP y.y.y.y.
(In case you're wondering, the reason is that we have two accounts with 
a service provider and different features and rates are tied to the two 
different accounts.)

So I was hoping I would be able to set the source IP that we use when 
talking to the two different SIP friends.  I see externip in general 
options, but is there nothing equivalent that can be set per user/peer?