For many people it is cheaper to call a geographic phone number (it depends on your tarriff).
So Government Departments can help citizens and small businesses save money in a recession just be publishing lists of numbers.
“The geographical number for the Self Assessment/PAYE DMB 0845 366 7816 telephone
number is 01506 476 066.”
“The geographical number for the Self Assessment card payments 0845 305 1000 telephone
number is 01726 209 025″
See: HMRC response
See also: saynoto0870.com