The MSISDN supports multiple verification flows with regards to the
MSISDN and MCC/MNC codes.
The client can discover availables verification methods using
the /discover endpoint.
The client /register to get an Hawk session that will be valid until
a /unregister call.
The client can verify one and only one number per session.
The client can use its Hawk session to generate as many BrowserID
certificates (valid for maximum a day) as needed until
the /unregister call, there is not automatic expiration of the Hawk
session.
A mobile number can be validated by multiple session (one per device
or per app. i.e: One for Loop and one for the Marketplace.)