It used to be where a lot of the area codes used to be alphabetized like Liverpool was 0L1 which is 051 or Newcastle upon Tyne was 0NE2 0632 but it all changed why is that? It’s a lot different now.
Anonymous
It's called "All-figure dialling", and it was introduced in the late 1960s when they both started running out of clever name-to-prefix codes and had to come up with a better system of assigning phone numbers to large and small cities, which just wasn't going to work with letter codes. The letter system also caused a lot of internationally dialed wrong numbers because different countries used different phone alphabets.