[gondo]

This is a terrible, TERRIBLE idea. Especially for people who move a lot. Phone numbers get reused. I am currently maintaining 4 SIM cards just to keep services relaying on them active. About 2 months ago I forgot to recharge one of those SIM cards and was locked out of one of my bank accounts.

[toohotatopic]

Why don't you register all services with one SIM and use a Dual-SIM phone to get cheap rates on another card?

Since we are talking about introducing a new identity system, isn't it easier to resolve the problems you mentioned than to introduce something new?

[gondo]

Because some services (banks) restrict phone numbers to only local (same country) ones.