"Make call without reg"
 

I found a tutorial suggesting this should be on Yes on my PAP2 and wasn't sure about the Ans call without reg.

Can someone explain to me exactly what this is and what difference it makes changing it to yes?

many thanks

SIP Proxy Server, as voxalot or any other VSP are, is not a must to IP telephony (VoIP). If you know the right address you can make a direct call to the other part and for that you don't need a SIP Proxy. In modern days, where you find any location on the internet through it's address name (not through IP address like 85.23.1.80), you need some king of service to resolve the name into an IP address. That is what DNS servers do to the World Wide Web and that is what SIP Proxy Servers do with IP telephony. When you register your phone with a SIP Server, you say to the world the way you can be found. Think it as a «white pages» service where your sip contact is translated to the IP address where your phone is.
The Linksys phones and ATAs have the possibility to receive direct IP calls without being registered at any SIP Server. Selecting to 'yes' the 'Ans. Call Without Reg.' option makes that, so your phone can receive a call despite it is not registered with your SIP Server. In other words, if you set that option to 'yes' you make your phone being able to receive direct call despite your phone is or is not registered with your SIP Server.
Regards,