BT in London

About BT’s London allocation

When BT is the range holder for +44 20 it means Ofcom recorded BT as the provider entitled to issue numbers from these blocks when they were first allocated under the UK National Telephone Numbering Plan. 1344 London-facing blocks sit against BT in the current Ofcom snapshot, each of which can carry up to ten thousand individual digits available for assignment to end customers.

London’s Greater London telecoms estate is shaped by London's catchment of roughly 8,982,000 residents: a dense urban exchange typically hosts allocations from several national operators in parallel, which is why you see BT’s blocks alongside other range holders on the same 020 code. Local switching capacity, historic Openreach exchange footprints, and BT’s wholesale routing arrangements all influence which blocks land in London rather than elsewhere on the national plan.

Treat this allocation as a starting point, not a verdict on any specific caller. UK numbers are portable, so the current carrier on a given 020 digit string may differ from the range holder shown — read Range Holder vs current provider for the distinction, and How Ofcom allocates UK phone numbers for the wider context behind the table below.