UCM6xxx collection support two varieties of SIP trunks: “Register SIP trunks”, mostly employed to attach with supplier’s trunk and “Peer trunks”, that can be used to interconnect multiple IP-PBXs. UCM6xxx https://zubairgdmi160739.wikienlightenment.com/7201339/the_single_best_strategy_to_use_for_service_providers_grandstream