AS21928 is T-Mobile US’s mobile network.
AS21928 belongs to T-Mobile USA, Inc.. DB-IP Lite attributes 13,120,000 IPv4 addresses in 25 ranges and 6 IPv6 ranges to it, all or nearly all of the IPv4 space in United States. The number is registered with ARIN in United States on 12 Jun 2002.
Does it publish a geofeed?
Not for the range we sampled (100.128.0.0 – 100.255.255.255): its registry record, and the record above it, link no RFC 8805 geofeed (checked 2 Nov 2026). Without one, location databases have to estimate where these addresses are used, which is a common reason customers of T-Mobile US see the wrong city. Customers can ask T-Mobile US to publish one; the evidence report drafts that request.
Shared addresses (CGNAT)
T-Mobile US hasn’t been documented as using carrier-grade NAT in a source we could check. To see whether your own connection is behind it, compare your router’s address on the CGNAT check.
IPv6
DB-IP lists 6 IPv6 ranges for AS21928, so customers can get IPv6 addresses, which databases place separately from IPv4.
Where its IPv4 space is used, according to DB-IP
Share of the network’s IPv4 addresses by DB-IP Country Lite. IP Geolocation by DB-IP.
IP ranges
IP Geolocation by DB-IP, ASN Lite, CC BY 4.0.
Using an address from this network? See which sources agree on where it is.
Sources
- DB-IP IP to ASN Lite (CC BY 4.0) · checked 5 Oct 2026
- NRO RIR delegated-extended statistics · checked 2 Nov 2026