[Asterisk-Users] differents contexts for a channel

[Ciprian Zetea]

Hi all, 
I have a tdm04b card with 4 fxo's connected to 4 POTS of a media
gateway. Supposing that I want to place the following calls:

Zap/1 dials Zap/2 (by placing in /spool/outgoing a call file which
dials a number corresponding to Zap/2)
Zap/3 dials Zap/2 (also placing another call file)
Zap/4 dials Zap/2 (also placing a call file) 
That's clear, in each situation Zap/2 will enter its incoming context
defined in zapata.conf.

My question is if it's possibile to change at runtime the context that
Zap/2 uses ?
If in Zap/2 to call comes from Zap/1 to enter a context and if the
call comes from Zap/4 to enter another...

Any help will be very much appreciated !!
Thank you all for your time..