Hi,
That is not a valid destination string since it contains the "SIP:", note this will be appended by the sip stack below and is not needed. For more information on the strings which can e used refer to the GC IP TUG:
www.dialogic.com/.../globalcall_for_ip_hmp_v12.pdf
"8.3.17.3 Forming a Destination Address String"
Regards,
Jeff