AS13205 British Telecommunications Limited

British Telecommunications Limited · registered in the United Kingdom

IPv4 addresses16,8966 prefixes · <0.001% of announced IPv4

Rank in United Kingdom#206largest network in GB by IPv4 space, of 2,074 · 0.02% of GB

Rank worldwide#6,767of 79,396 networks with IPv4

IPv6noneno IPv6 routes announced

CountryUnited Kingdom2,261 ASNs registered there

Open AS13205 in ASN lookup Look up an IP in this network (31.11.56.1) All networks in United Kingdom

IPv4 prefixes

All 6 prefixes, in address order.

31.11.56.0/23
78.109.0.0/21
78.109.8.0/22
78.109.12.0/22
217.140.0.0/20
217.140.32.0/19

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IP-to-ASN data: iptoasn.com (public domain). Snapshot downloaded 2026-11-11, refreshed daily. Ranges are what each network announces in BGP, not registry allocations. Data sources