SIP registration with no authentication

apologies if this has been covered before, I have looked through a mass of posts, both here and elsewhere.

I have asterisk set up with a SIP client (xlite), and a public SIP trunk. I want to be able to dial out over the public trunk from xlite, by dialling 9 xxxxxx.

although x-lite can digest authenticate, this is only being used for testing. I want to use a PBX as a client, but the PBX can neither REGISTER, or authenticate 407’s when INVITEing.

how do I configure asterisk to not authenticate the client?

the context from my sip.conf for the client is:

[Scotty]
type=friend
regexten=200
secret=donttell
context=default
host=dynamic
insecure=very

the context for the SIP provider from sip.conf is:

[146.101.148.200]
type=peer
fromdomain=sip.voiceflex.com
secret=???
insecure=invite
canreinvite=no
host=dynamic

finally, to dial out from extensions.conf, i have:

[default]
exten => _9.,1,Dial(SIP/${EXTEN:1}@146.101.148.200,30,r)

With the setup like this, dialling 9XXXXXXX from the client results in both 407 authentications passed to the client, and after the client authenticates, 180 RINGING followed by 503 service unavailable. could anybody shed some light on this for me please?