Cant we have same extension in different context?
This is what we we want in same pbx server?
IVR Company A
Extensions: 101,102,103,104 etc. Company B
IVR Company B
Extensions: 101,102,103,104 etc.
SIP usernames =! Extensions
You have to use unique sip usernames to be identified inside dialplan for mapping to extensions
Exten => 101,1,Dail(sip/custA_user1)
Exten => 101,1,Dial(sip/custB_user2)
Hope this makes it clear.