FOI request (FOIR-281961703)

As part of the Change Intelligence team at Ordnance Survey, I would like to find out some information about emergency telephones and their location, particularly along the coastline. From doing some initial research it seems that many local authorities manage coastal telephones.  

Therefore, I am enquiring whether you have a list of emergency coastal telephone locations, as a geospatial dataset or just a list of the ones the council provide? In addition, do you have any contact with BT regarding phone maintenance; information would help towards contacting them to locate and map coastal phones across the country.  

If you can provide any information at all or would be able to put me in contact with someone who may know any details, it would be greatly appreciated.