Phone charges imposed by some hospitals "prey on the poorest and most vulnerable," says a Welsh Assembly Member.
Mobiles should not be banned outright in hospitals, regulators say
Torfaen AM Lynne Neagle said patients could pay as much as 49p a minute for a local call.
She and the British Medical Association want the Welsh health minister to look at allowing mobile phones in hospitals.
One company said it was working with the Department of Health to see if costs could be reduced.
Many NHS trusts have a ban on mobiles in hospital buildings, which is often explained as necessary to prevent electromagnetic interference with medical equipment.
The Medicines and Healthcare Products Regulatory Agency (MHRA) points to 10 reports in the last decade of mobiles interfering with infusion pumps, used to administer fluids.
But it has said hospitals should not impose a blanket ban on mobiles.
Hospital trusts also say mobiles could potentially disrupt the peace and quiet patients need, with camera phones posing a possible intrusion on patient dignity and confidentiality.
Ms Neagle, who also chairs the assembly all-party group on cancer, said her call was based on a series of independent reports into the charges of alternative phone systems supplied at hospitals.
She said many of the concerns centred on Patientline, a communications system used in three Welsh NHS Trusts: Cardiff and the Vale, Gwent and North West Wales.
She said: "A number of independent reviews have emphasised the unacceptable cost of phone calls for patients, and it is time we acted on this research.
"The idea that people should have to pay 49p a minute to call a loved one in hospital is just not on - especially as recent scientific evidence is now available which shows mobiles can be used safely in hospitals.
"The news that Scottish health officials are considering lifting the ban on mobile phones in their hospitals should be a spur for action in Welsh NHS trusts."
Dr Tony Calland, of BMA Wales, described the call charges as some hospitals as "just another tax on the sick and the vulnerable".
He said: "One of the most expensive bits is that they not only have to pay for outgoing calls but they have to pay for incoming calls as well, over which they have no control."
Michael Summers, chairman of the Patient Association, said: "As long as mobile phone use is properly regulated in hospitals there is no scientific reason why they should be banned."
Charles Dalton, head of health and safety at Cardiff NHS Trust, said it allowed mobiles to be used outside hospital buildings, and had formed a working group to look at allowing mobile phones in non-clinical areas.
He said: "There is a risk for using mobile phones very locally to some medical equipment. The risk is quite small. We would generally not endorse using mobiles in clinical areas."
The MHRA has said there was confusion over whether phones ought to be banned outright.
Its experts said they should be restricted only where specialist equipment was used, as in intensive care and specialist baby units.
Patientline said it charged as "little as it is able" to run the service without the NHS having to contribute, and was yet to make a profit due to a "heavy investment programme".
The company said it was working with the Department of Health to see if the service could be made cheaper for users.
A spokesperson said: "What we offer is not an essential part of someone's care but people may freely choose whether to use the service."