As far as i know, my customer has 1 sip line with 4 channels, and by now all the trunks are set as DIL and he can receive and make outside call. Maybe it's not the way it should have work, but it work right now. As it have only one DID, is it right for me to change the trunk to DID? and if i have to set a trunk as DISA, how the system know that he have to select that trunk when i have only 1 sip line with 4 channel?