[asterisk-users] Zap Channels Collide (Incoming & Outgoing)

[Forrest Beck]

I have a client that is using the Sangoma A200DE with two phone lines  
attached.

The problem is:

They use their phone (Grandstream GXP2020) to dial out of the system.
Instead of getting ringing, there is someone on the other end of the  
line that happened to dial in at the exact same moment.

So now they are stuck talking with this person, instead of the one the  
originally called.

The ZAP channels are in a dial plan context that instructs it to just  
dial the office phones.

[zap1]
exten => s,1,Dial(SIP/1001&SIP/1002&SIP/1003)
exten => s,n,Voicemail(1000 at vm)

Anyone know how to get around this?

Thanks!