The Welsh government is investigating after a newspaper inquiry showed that patients telephoning to book a GP appointment are paying at least five times the normal rate through premium phone lines.
Wales on Sunday revealed that the 0844 prefix, used by dozens of health centres around Wales, costs callers up to 5p per minute from a landline, and considerably more from a mobile phone. Communications regulator Ofcom advises public bodies to use the cheaper 03 prefix, but cannot insist they do so.
"It's up to the surgery itself, we do not regulate them," an Ofcom spokeswoman told the newspaper. "Any company or business can take them on. However, for services for the NHS, we have encouraged clinics to talk to the Department for Health to use the cheaper 03 numbers.
She said that numbers were allocated in blocks of thousands and that it was up to businesses and communication providers which ones to take. The 0844 and 0845 numbers were useful for routing calls and call management systems, she added.
The Welsh Assembly Government had previously advised GP practices to move from premium rate numbers to the cheaper 0844 or 0845 numbers. Health Minister Edwina Hart is now to launch her own probe following the complaints.