[Asterisk-Users] functional difference: canreinvite=yes, no, or update

[Kevin P. Fleming]

Freddi Hansen wrote:

> what about letting this logic be followed by a dialplan macro that gets 
> called to make the decision. May sound weird but we have a 'network-id' 
> attached to each sip-user.  That network-id contains the public fixed-ip 
> of the users network plus a unique name. If the network id's is matching 
> and both users are on their 'home-network' then we do re-invite. This 
> allows us to deal with special cases where people are behind 
> double/triple nat a.s.o. . In other words it allows the Asterisk user to 
> overrule the default behavier.  It's allows us (as an  ITSP) todo a safe 
> re-invites on known networks to save on customers (and our) bandwith. 
> Our hack is really ugly and it would be a like a dream to have this 
> stuff in CVS.

I don't think it would be logical (or efficient) have this run in a 
dialplan macro at all; that would require creating a channel, copying 
variables into it, etc.

I have been thinking about extending the Asterisk expression evaluator 
to allow it to call out to res modules to do the evaluation (passing in 
the channel variables as entities or something)... this would allow you 
to use res_perl or a future res_python or something to do more complex 
data manipulation.

However, even that is only a small part of the solution, since chan_sip 
treats all this information as static right now, and extending it to 
support a dynamic result would take some work.