Anonymous inbound SIP fails

I have freePBX 2.9 running with Asterisk 1.6

I have allow anonymous set to yes and allow guest in SIP settings module set to no

When I try to add my number to for anonymous inbound calls I get a 401 error stating that authentication is require by my sip server

Other than these two settings, what else might I want to look at to get anonymous sip working?

Do not point records at your own PBX. Use your VSP instead and point to your number there. Most US based VSPs allow unauthenticated calls to their users.

Check also,24665462