The code is incomplete...
01380 is Devizes
01381 is Fortrose
01382 is Dundee
01383 is Dunfermline
01384 is Dudley
01386 is Evesham
01387 is Dumfries
013873 is Langholm
01388(2) is Stanhope
01388(3) is Bishop Auckland
01388(4) is Bishop Auckland
01388(5) is Stanhope
01388(6) is Bishop Auckland
01388(7) is Bishop Auckland
01388(8) is Bishop Auckland
01388(9) is Bishop Auckland
01389 is Dumbarton
Source: British Telecom