Most of the Merseyside region has the same four digit dialling code.
The iconic 0151 prefix spans across Liverpool, Wirral, Knowsley, as well as some parts of Sefton.
But venture any further north than Hightown, and the code changes to 01704.
The dialling code dates back to the old rotary telephones which used to be in every home, pub and office
Rotary telephones may now obsolete but they were once in millions of homes across the country and plenty of Liverpool residents will remember them clearly.
The Southport 01704 dialling code intersects Merseyside and Lancashire. Local phone numbers within the code are just six digits long.
Before the 16th April 1995 known as PhONEday which changed telephone area codes by inserting a 1 at the beginning. The area code was 0704.
This was because the first two characters are taken from the letters S and O in Southport. On an old rotary dial telephone this was entered by dialling the numbers 7, 0 and 4.
The areas banded together are generally cities and large towns, rather than local government areas, according to Ofcom.
Dialling codes do not correspond to specific political boundaries and St Helens, for example, also has a different area code.
British Telecom, now known as BT, was formed in 1981, and then assumed control of the UK's telephone network.
Today BT is a global player in telecommunications, offering a range of technology to households and companies. BT is also now a leading broadcaster of sport, showing Premier League football.
BT still has a statutory obligation to maintain a network of phone boxes in the UK. The original red phone box was designed in 1924 by architect Sir Giles Gilbert Scott, who also created Liverpool's Anglican cathedral.
There used to be nearly 80,000 red phone boxes in the UK but that figure has now reduced to around 10,000.
Locations using 01704 numbers include:
Ainsdale
Birkdale
Burscough
Churchtown
Formby
Halsall
Rufford
Scarisbrick
Southport
