It depends on where the phone number is ("rate center" = area code plus first 3 digits of local number). If you post that here - e.g.
613-832-XXXX - people may be able to give more precise suggestions.
Voip.ms can certainly do this for many rate centers. (I have an answer-only number with them that copies the voice mail to email and deletes it from the voice mailbox).
Cost is typically between $1-$2/month, +$0.015/min for the incoming calls. Some rate centers are more expensive than others.
You do need a soft phone to set up the outgoing voicemail message, however. (Uploading a recording for this is a long-awaited feature).
Also see the posting by MartinM in this thread
»[Anveo] Free Porting Special Extended!
for a current Voip.ms porting promotion.