if an UA registers an ar two times with same +sip.instance and reg-id, will registrar replace the earlier one with the new one? this kind of thing can happen, for example, when the UA has lost connection with outbound proxy and re-registers. based on what i have understood from the ob rfc, registrar should replace the old location entry with same +sip.instance and reg-id, but i haven't looked kamailio code. if it does, things get simpler in t_serial, because i don't need to care about reg-id at all and can just compare +sip.instance values of contacts. -- juha