At a glance
- ASN
- AS21928
- Organization
- T-Mobile USA
- Category
- Mobile ISP
- Region
- United States
AS21928 - T-Mobile USA
Major US mobile carrier ASN for handset and 5G data traffic. Use this page as a quick ASN reference before deeper DNS, WHOIS, and routing checks.How to use this ASN page
Use AS21928 as a routing anchor when investigating traceroutes, hosting ownership, or provider reputation. ASN pages work best when combined with live IP checks.
- Map an IP to an ASN with the ASN lookup tool.
- Check ownership context with WHOIS / RDAP.
- Validate mail/security posture with blacklist checks.
AS21928 related tools
More ASN pages
Browse the full ASN directory for additional cloud, ISP, and backbone networks, or open the ISP directory to pivot by provider.
Why AS21928 appears in lookups
IP ranges are announced through BGP by autonomous systems like AS21928. When you resolve an IP to ASN, you identify the network currently advertising that route.
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AS21928 FAQ
What does AS21928 mean?
AS21928 is an autonomous system number used by BGP to identify a routing domain on the public internet.
Can one ASN announce many IP ranges?
Yes. Large providers typically announce many prefixes across regions and services.
Does ASN identify exact ownership of every IP?
Not always. ASN shows routing origin context, while WHOIS/RDAP provides registration-level ownership details.