Verified Nov 1, 2026 · Source: NANPA CO Code Assignment

Which carrier owns 518 numbers?

62 holders appear in the 775 number blocks assigned in 518 of the 786 possible. Verizon holds the largest named share at 35.9%, ahead of AT&T at 11.5%. A further 14.3% sits with holders outside the national carriers, counted together: competitive local exchange carriers, VoIP providers and the resellers behind app-based numbers. These are blocks allocated by NANPA, not customers. Number portability means a block registered to one carrier can be full of numbers now served by another, so the share describes the registry, not the market. The top 16 holders shown account for 100.0% of assigned blocks. Blocks are allocated to rate centers; the largest in 518 are ALBANY (200), SCHENCTADY (50) and GLENSFALLS (45).

Share of assigned number blocks

Verizon 35.9%

Other CLEC / VoIP 14.3%

AT&T 11.5%

Windstream 7.6%

Lumen 7.2%

T-Mobile 5.4%

Charter 4%

Frontier 3.9%

Onvoy 3.2%

Bandwidth 2.5%

Peerless 2.1%

Spok 1%

American Messaging 0.5%

Altice 0.5%

Telnyx 0.3%

Vonage 0.1%

Of the 775 blocks assigned in 518 out of 786 possible; the 16 holders shown cover 100% of them. Each block is 10,000 consecutive numbers. Bars are scaled to the largest holder, not to 100%.

Why this is not “who your caller uses”

Number portability means a subscriber keeps their number when they change carrier, while the block stays registered to whoever originally received it. In a code that has been in service for decades, a large share of numbers are served by a carrier other than the registered holder. The table above is an accurate picture of the numbering registry and a poor proxy for market share.

Where the blocks sit

Blocks are allocated to rate centers – the billing geography, not the carrier. NANPA truncates their names to ten characters, and in large metros they are telephone zones rather than places, so we leave them unchanged rather than guessing. Showing the largest 5 of 135.

ALBANY200

SCHENCTADY50

GLENSFALLS45

TROY34