[Asterisk-Users] iax vs iax2 connections

[Rich Adamson]

Been meaning to ask this for some time... no big deal, but curious.

I have a single register statement in my iax.conf for iaxtel like:
 [general]
 port=5036  
 register => npi:mypassword at iaxtel.com
 <snip>

However, when I restart *, I see:
 Registered to '69.73.19.178', who sees us as 205.221.193.101:5036
 Registered to '69.73.19.178', who sees us as 205.221.193.101:4569
which suggests both iax and the iax2 protocols in use. The 
'iax show registry' and 'iax2 show registry' confirms it as well.
I only see this with iaxtel.com links, not with other iax links.

If I remove the register statement, neither iax or iax2 is active.

Is this something specific to the iaxtel.com box, something that I'm
missing in my config, or what?