Media playback is unsupported on your device

Why does my phone think it is abroad?

4 April 2014 Last updated at 22:02 BST

It is known as "inadvertent roaming", and it means that your mobile phone behaves as if it is abroad.

The phenomenon affects mobile customers in the south of England, who are picking up French network signals - as well as other parts of the UK.

Zoe Kleinman reports.