[Asterisk-Users] ser --> sip.conf --->extensions.conf, variable context

[Iqbal]

Hi

If I have ser sending calls to asterisk, is there a way to get a 
different block called in sip.conf for each call (based on some 
variable, NOT username, From:), if not and they all hit one block which 
has contect=abc, then when that context is called/matched in 
extensions.conf,  how can I have diff features for various groups of users.

EG lets say I have a large company with 4 departments (not so large), or 
even 4 separate companies who are on VoIP

Now they all have there own dialplans, some want voicemail, some may 
not, others may want to use call pickup, and group calling, in order to 
stop them picking up each others calls, I think I would need them to sit 
in their own contexts within extensions.conf, and so there own 
extensions can all be defined on their internal criteria.

Or is there a better way of doing this, in short how can I restrict one 
group of user and prevent them from interfering with the others, without 
having a separate asterisk box for each user, has anyone used asterisk 
in a multiple company hosted setup

tks
Iqbal