For the same reasons ($1/month<<$8/month, even though it means I burn a precious NANPA DID), I've set up the same without writing a single line of code.

With VOIP.ms, I ordered a DID and set it to auto-answer any call. They have a voicemail feature you can use, so it handles the recorded message and recording after the beep. Voip.ms then emails you the voicemail (nice for recordkeeping). If your cellular provider has an email to SMS gateway, you can forward the email there, and you'll see the callerid in the subject, but no CNAM to speak of.

Once working, I set my cellphone to auto-direct any unanswered calls to the DID I setup.

Here's how some Canadians are doing it: http://awslookup.com/free-voice-mail-on-wind-mobile/