exten => _X.,1,Set(FIXED=${CALLERID(number)})
exten => _X.,2,CUT(FIXED2=${FIXED},-,2)
exten => _X.,3,Noop(${FIXED2)})
exten => _X.,4,Dial(${TRUNK1}/${EXTEN})
exten => _X.,5,Congestion

Outputs this:

 Executing Set("SIP/3055741495-b7001be0", "FIXED=3055741495;phonecontext=+") in new stack
    -- Executing Cut("SIP/3055741495-b7001be0", "FIXED2=3055741495;phonecontext=+|-|2") in new stack
    -- Executing NoOp("SIP/3055741495-b7001be0", "") in new stack
    -- Executing Dial("SIP/3055741495-b7001be0", "Zap/g1/7349569957") in new stack