[ksajadi]

Yes, but it adds insult to injury. One of the suggestions by Twilio is to use their service to check the number and send only to mobile numbers. The issue? Twilio charges per call for that service! So you pay them to "possibly" stop you paying them more and fraudsters. The whole thing stinks

[blowski]

Is there some kind of regex for premium rate vs standard numbers?

[Symbiote]

In some countries.

For example, all UK mobile phone numbers begin 07 (i.e. +44 7), fixed/special rate 08, and premium rate 09.

But SMS also has "short codes", which is probably what's being abused here. 5 or 6 digit numbers, usually used for things like "Text 12345 to donate €2 to this charity" or "Send 'CXM' to 12345 and receive a message telling you when the next bus comes to this stop, costs 10¢".

https://en.wikipedia.org/wiki/Telephone_numbers_in_the_Unite...

https://en.wikipedia.org/wiki/Short_code

[sk5t]

Might libphonenumber be of some help?