Are there common practices or extensions that could help with validating SMS phone numbers? Not their format, but to validate that the contact really owns that number.
For example: as a user, I fill in a form with my mobile phone number. The system sends me an SMS with a code to validate, and I have to enter that code in a form.
I understand email in CiviCRM does not explicitly have that functionality either, but there are features such as double opt-in for Groups, and email validation for Petitions. Although I guess this goes towards having some sort of "verified" status (tag/group/field) for contacts.
