SIP provider authenticates by IP - configuration help

Hi,

I have looked through the forums but i cant find the answer to this one..

I have a Trixbox 1.6 and a new Outbound Sip Provider. This provider (Teleware) authenticates by IP address not by a registration string. I have applied all of the settings they have given me in the following configuration:
They sent:
'Here are your SIP trunk configuration details.

SIP Trunk Number - 11xxxxxxxx
Our IP Address – xxx.95.xxx.27

The new DDI is 01xxx 2xx xx3 and the presentation CLI has been set up as the existing number 01xxx x2x x7x as per your request.'

I have configured a SIP trunk with the following config:

username=11xxxxxxxx
host=xxx.95.xxx.27
type=friend (tried peer also)
fromuser=11xxxxxxxx (tried with and without this)
dtmfmode=rfc2833 (tried with and without this)
insecure=very (tried with and without this)

The provider doesnt offer a password with the username therefore the SIP wont register and when calls are attempted trixbox immediatly responds with Channel unavailable.

If i enter information into the register string like username:pw@IP_ADDRESS/DID or DDI it just produces Authentication errors which is correct as there is no system to respond to it from the providers end.

Please help..

Thanks
Si.