If DPA finds Facebook in breach of GDPR they will be ordered to do it with additional fines for non complying.
Art. 58 GDPR Powers point 2:
> Each supervisory authority shall have all of the following corrective powers:
> (e) to order the controller to communicate a personal data breach to the data subject;
> (f) to impose a temporary or definitive limitation including a ban on processing;
> (i) to impose an administrative fine pursuant to Article 83, in addition to, or instead of measures referred to in this paragraph, depending on the circumstances of each individual case;
If FB still refuse, it will end up in the court.
If the courts agree with DPA, then FB will be ordered by the courts as well.
Courts can choose their way to force companies to comply with their orders.
Technically it's not a problem, it's kinda easy to filter phone numbers by country and (less reliable) by carrier. Then you either can use country local SMS gateways or potentially give it to the carrier in question and let them do it.
Again the problem is the legal basis.
Preferably a change of law should:
- make it legal for the goverment to do the contacting, including by passing it to the carrier associated with the number
- require carriers to send the massage (to avoid auto matic SMS spam detection problems). Through you give them some (small!) amount of money for their (lets be honest) small amount of additional work.
Actually, the processing of this data itself is probably a breach of GDPR.
Just imagine getting a SMS (chain):
> You phone number and some of your data (<listed>) had been involved into a Facebook data breach. While Facebook is required by <insert law> to inform you about this breach they insists of not complying with the law and keeping they users in the dark. As such we <insert EU/local government agency> decided to do so. More information can be found here: <link to official EU site + link to local government sites with official translations>