exten => 556,n,Set(OFFICE_START=3100)
exten => 556,n,Set(OFFICE_END=3699)
exten => 556,n,GotoIf(${CALLERID(num)} = _30XX?spyon:spyoff)
exten => 556,n(spyon),GotoIf($[${SPYNUM} >= ${OFFICE_START} & ${SPYNUM} <= ${OFFICE_END}]?spyenabled:spyoff)
exten => 556,n(spyenabled),ChanSpy(SIP/${SPYNUM},wq)
exten => 556,n(spyoff),NoOp(spyoff)