On a motorway, why might it be better to use an emergency roadside telephone rather than a mobile phone?

Explanation: On a motorway, it's best to use a roadside emergency telephone so that the emergency services are able to find you easily. The location of the nearest telephone is shown by an arrow on marker posts at the edge of the hard shoulder. If you use a mobile, the operator will need to know your exact location. Before you call, find out the number on the nearest marker post. This number will identify your exact location.

Category: Motorway rules (Motorcycle Theory 2021)

References: The Official DVSA Guide to Riding: Section 11, Highway Code: Rule 275