I know some people dislike them, but personally, I'd like to see missed call nofications sms messages.
I believe some of the dislike was because of how poorly Rogers originally implemented the Who Called service, with customers receiving the text messages even if the caller left voicemail or if a call simply went unanswered. Neither of those things were supposed to happen.
Wind also has this and calls it Missed Call Service.
Obviously, the text should only be sent out to the Public customer if the receiving phone doesn't ring (no signal or phone off), and it shouldn't be sent out if the phone rings or if a voicemail message is left.