Toronto Asterisk User Group

I've started to dabble in VoIP a bit, with the ultimate goal of moving my home to an Asterisk-based PBX with VoIP service to the PSTN.

Currently, I run a simple home network sitting behind a NAT/firewall. I am reluctant to change this configuration.

For telephone service, I would like to set up a dedicated Asterisk box (a Rowetel IP04 to start with) within my network, and migrate my inside phone system to the FXS ports provided on the box.

Initially, I'd connect the single FXO port to the PSTN (I still subscribe to a dedicated Bell line), thus connecting the inside to the outside.

However, with the networked facility of the IP04, I'd like to ultimately move that outside connection to VoIP, coming through my firewall to my NATed IP04.

If I understand correctly, this rules out SIP as a carrier protocol (at least for calls with endpoints outside my LAN) because that protocol can't survive Network Address Translation.

My latest idea would be to use the IAX protocol, and connect with some outside peer who would act as the SIP endpoint, and transport the VoIP to/from me via IAX.

In addition, I figure that this outside peer should be able to provide me with a PSTN connection with DID, so that I can originate and receive POTS telephone calls as well.

What do you think? Is this the way to go, or should I look in a different direction?

If this is the preferred/recommended approach, then can anyone suggest a local (Brampton/Toronto) VoIP provider that can
a) deal with a single home user (as opposed to a business/bulk client),
b) accomodate IAX,
c) provide realistic rates for incoming and outgoing PSTN calls,
d) won't bundle unnecessary facilities into the package (do I /really/ need *their* voicemail or caller-id offering, given the facilities available to me within Asterisk?)

Suggestions?