Dear Sir, Is it possible to create two transport with same type, ie TCP only when creating transport it will call pjsip_tpmgr_register_tpfactory but this function check for same transport that already exist for (p=mgr->factory_list.next; p!=&mgr->factory_list; p=p->next) { if (p->type == tpf->type) { status = PJSIP_ETYPEEXISTS; break; } what I want to do is to create two TCP transport each listening different interface adddress. create and destroy will no good for me because STUN binding may take long time. Regards Yeffri