Why are people allowed to use cell phones in some hospitals but not in others?

Cell phone usage in hospitals depends on individual regulations. According to the latest studies, it is not necessary to prohibit the use of mobile communications in hospitals altogether, since a distance of 3 meters is sufficient so that no disruptions to medical devices will be expected.

However, disruptions to medical devices by cell or smartphones cannot be fully excluded. For this reason, their usage is usually prohibited or limited, above all in operating theaters and on intensive care wards.
Mobile communications users should always observe the regulations and usage information provided in hospitals and doctors' treatment rooms and, if applicable, switch their mobile phones off.