exten => 911,1,NoOP(Dialing 911)
exten => 911,n,Set(dialstring=${GLOBAL(TRUNK)}/${EXTEN:${GLOBAL(TRUNKMSD)}})
exten => 911,n,GoSubIf($[${EXTEN} = 911}]?sub_get_location_emergency,s,1:)
exten => 911,n,Dial(${dialstring})