Can't make outbound calls via sip trunk

All the above data (proxy, host, username, secret) is provided by the ISP.
The problem with outbound call is:

 -- Executing [s@macro-dialout-trunk:30] Dial("SIP/2002-00000424", 
"SIP/Telecom/187@06614******,300,T") in new stack

The number i dialed is 187 and the pbx added @0661

This is the section of the macro involved:

exten =>s,n,Dial(${OUT_${DIAL_TRUNK}}/${OUTNUM}${OUT_${DIAL_TRUNK}_SUFFIX},${TRUNK_RING_TIMER},${DIAL_TRUNK_OPTIONS})`

i think the problem is in this variable:
${OUT_${DIAL_TRUNK}_SUFFIX}