Whlst looking for something unrelated, I noticed that the UK Crime and Policing Bill, sections 80-82 imposes restrictions on possession of “SIM Farms”, where “SIM farm” means “a device which is capable of using five or more SIM cards simultaneously or interchangeably, for the purpose
of—
(a) making telephone calls to persons at telephone numbers allocated in
accordance with national or international numbering plans, or
(b) sending messages to, or receiving messages from, such telephone
numbers.”
Whilst hopefully the good reason defence, included, would cover everyone here (this seems to be intended to address scammers using them), anyone in the UK using or planning to use “GSM” gateways should probably get advice on the impact of this legislation.