Domain names and Asterisk

I’ve search but haven’t found my specific question.

I want to know if it’s possible to point to my Asterisk server behind a NAT router and use this as a handle.

So I could give as my SIP ID and someone opens their SIP client, enters and I get the call?

Or does it have to be an email address at a domain?

I’ll be the only one using it, so not really bothered about needing to have more than 1 user.

Using a sub-domain is ideal for me, as I can keep my files hosted with the main domain, separate with a host online.

I’ll also be logging into the SIP server using my domain, from my iPhone and Mac when traveling (obviously the SIP server is running at home) and be able to still receive calls using the domain.

Also, could multiple domains be used on the same Asterisk server with the server directed the call to a certain user depending on which domain it’s coming in from?

Eg: call is made to goes to Henry
call is made to goes to Cuthbert

Finally, if I did want to have email address format aliases on Asterisk, can this be done at a sub-domain, such as

If the above is possible and there’s nothing I should really know before jumping in and doing it, I’ll have a good weekend setting up my Asterisk server.

Thanks in advance.