I have been given the following settings for connecting to a voip provider. The names of the fields match my snom phone, and when configured, the phone both makes and recives phonecalls without issue. I am trying to put the same values in asterisk, but there seems to be one field that doesn't seem to exist in asterisk - that of outbound proxy all suggestions welcome SIP headings account = user password = secret registrar = host = registrar.provider.com outbound proxy = ?? = nat.provider.com:5065 If I put in an extra field of port=5065 it doesn't register (in sip show registry) with either of the above addresses in the host box. Putting registrar.provider.com in the register => string and nat.provider.com in the host makes outbound calls fail, putting registrar.provider.com in the host and nat.provider.com (with or without the :5065) in the registrar doesn't allow incoming or outgoing calls putting reistrar.provider.com in both host and the register => string allows outgoing but not incomming firstly, what does the outbound proxy do? secondly, can anyone advise on settings for this senario? does asterisk have this concept in its SIP client? Thanks David