What Is My ISP

What an ISP actually is

Your ISP, strictly speaking, is the company that sells you internet access. But the networking world slices providers into tiers based on how they connect to the rest of the internet, and that hierarchy is why the name shown here often surprises people.

A Tier 1 provider peers with every other major network for free, exchanging traffic without settlement payments. These are the backbone operators: Lumen (formerly CenturyLink), NTT Communications, Telia, GTT, and a handful of others. They collectively form the core of the internet.

A Tier 2 provider has its own infrastructure in a region or country but purchases transit from at least one Tier 1 to reach networks it cannot peer with directly. Most national ISPs fall here. They own fiber, data centers, and exchange points, but they pay for global reach.

A Tier 3 provider buys transit all the way up, typically from a Tier 2 or a Tier 1 reseller. Many small local ISPs, fixed-wireless operators, and mobile virtual network operators (MVNOs) are Tier 3. They own the last mile to your house but rely entirely on upstream capacity they purchase wholesale.

This hierarchy is why the name on this page often does not match your invoice. Routing databases record the network that registered the IP block, which is usually the Tier 2 or Tier 1 entity. The Tier 3 reseller you actually pay is invisible to the global routing system.

ASN: the number behind the name

The ASN this page displays is a BGP (Border Gateway Protocol) identifier. Every independently routed network on the internet gets one. The original standard, RFC 1930, defined 2-byte ASNs with a range up to 65,535. The pool was exhausted by 2010, so RFC 6793 extended the format to 4 bytes, allowing values up to 4,294,967,295. New allocations today come from the 4-byte range.

In BGP terms, an ASN represents a routing policy: which IP prefixes the network owns, which neighboring networks it connects to, and what paths it advertises or filters. Every BGP-speaking router on the internet maintains a table of these advertisements to determine how to reach any given address.

Large providers often operate multiple ASNs. A major carrier may have separate ASNs for its consumer broadband, enterprise services, and international operations. That is why the same company can appear under different ASN names depending on which part of their address space your IP falls in.

An ASN is a more precise identifier than an org name for technical purposes. When filing a ticket with a CDN, cloud provider, or network operations center about a routing or peering issue, give them your ASN. It maps unambiguously to a network in their BGP table; an org name does not.

How this page finds your ISP

When your browser connects to this site, the request arrives with a source IP address. I read that address from the request headers. From there, two lookups happen in sequence.

First, the IP is mapped to an ASN using the Team Cymru IP-to-ASN service, a DNS-based lookup maintained by the security research community. A query to a special DNS zone with your IP reversed returns the ASN that currently announces that prefix in the live BGP table. This is as close to ground truth as publicly available data gets; it reflects real routing, not a monthly export.

Second, the ASN resolves to an organization name through WHOIS records at the relevant Regional Internet Registry (RIR). ARIN covers North America, RIPE covers Europe and the Middle East, APNIC covers Asia-Pacific, LACNIC covers Latin America, and AFRINIC covers Africa. Each registry stores the legal registrant of the address block.

What these two lookups cannot tell you: which reseller you pay, what speed tier you are on, or whether the physical cable entering your house is fiber or copper. Those details live inside the ISP's own systems, not in public routing data.

When the name shown is not your ISP

Four situations reliably produce a name that surprises you.

VPN exit nodes.When you use a VPN, your traffic exits from the provider's datacenter IP. This page reports that VPN operator's ASN, often a hosting company like M247, Datacamp, or AS-CHOOPA (now Vultr), not your home broadband. That is correct behavior. Checking this page after connecting is a reliable one-second confirmation that your VPN is actually routing traffic.

Mobile carrier regional gateways. Carriers route all mobile data through regional network access points before handing it to the internet backbone. I ran into this directly when filing a support ticket with a Pakistani carrier: this page showed PTCL (Pakistan Telecom), the correct upstream transit provider, but the company on my invoice was a local reseller leasing capacity from PTCL. The ASN pointed at the right autonomous system but the wrong brand. On mobile networks across South Asia and Africa, you will almost always see the wholesale carrier, not the virtual operator you pay.

Corporate and university networks.Inside an enterprise or campus network, all traffic exits through that institution's registered IP block. You will see the university name or the company's IT department ASN even on a contractor laptop or guest Wi-Fi on the same network.

CDN and proxy egress. Some businesses route outbound internet traffic through a security proxy or SASE platform. Employees on such networks may see Cloudflare, Zscaler, or a corporate egress provider rather than the underlying broadband ISP.

Actually useful reasons to know your ISP

Most pages that show you your ISP exist because VPN marketing departments need something to display before and after a purchase. Here are the reasons I actually reach for this information:

• Support ticket escalations. When you call an ISP about a routing or peering issue, the network-ops engineer asks for your ASN and prefix, not your account number. That is how they identify which routing segment is affected. Having the ASN ready from this page saves the 10-minute lookup at the start of the call.
• ASN allowlists on cloud services.AWS, GCP, and Azure security groups can restrict inbound traffic by IP range. Some organizations allowlist entire ASNs for their office egress. If a colleague cannot reach an internal tool from a new location, checking whether their ISP's ASN is on the list is the right first diagnostic step.
• VPN confirmation.Connect to a VPN, refresh this page, confirm the ISP name changed to the VPN provider's hosting company. If it still shows your home broadband, the tunnel is not routing browser traffic. Faster than a full DNS leak test for a quick sanity check.
• Geo-routing investigations. Streaming platforms, pricing engines, and ad networks make decisions based on ASN type. Residential ISPs are treated differently from known datacenter ASNs. If content refuses to load despite the correct country showing, the ASN classification might be causing it.
• Network research and threat intelligence. Security teams use ASN data to understand traffic origins, block abusive IP ranges, or build threat-intelligence feeds. If you are analyzing logs, the ASN tells you more about a source than the raw IP.

Finding your ISP from the command line

If you want to verify what your connection reports without trusting a webpage, all three major platforms have reliable options. I keep the Linux version aliased on every machine I manage.

Linux and macOS

# Quick org lookup via ipinfo.io
curl -s https://ipinfo.io | jq .org

# Raw WHOIS with registry record
whois $(curl -s ifconfig.me) | grep -i "^org\|^netname\|^descr" | head -5

The first command hits ipinfo.io's JSON API and extracts the org field directly, which includes the ASN number and name in one line. The second runs a WHOIS lookup on your public IP and filters for the lines that identify the registrant. RIPE records use netname: and descr:; ARIN records use OrgName:; APNIC records use descr:. Adjust the grep pattern for your region if needed.

Windows (PowerShell)

(Invoke-RestMethod https://ipinfo.io).org

This single line fetches the same JSON from ipinfo.io and prints the org field. If the output shows a VPN provider or datacenter name instead of your home ISP, your traffic is being routed through something between your browser and the internet.

ISP detection sources compared

Several public and commercial datasets map IPs to organizations. They differ in freshness, accuracy, and cost.

For most diagnostic purposes, a combination of Team Cymru (for the ASN) and MaxMind or IPinfo (for the human-readable org name) gives you the most accurate result. That is the approach this page uses.

Frequently asked questions

What is the difference between my ISP and my modem manufacturer?

Your ISP sells you the connection to the internet. Your modem manufacturer built the hardware that connects your home to the ISP's network. They are completely separate. Companies like Netgear, ARRIS, and Motorola make modems; they have nothing to do with who routes your traffic online. The modem is just the bridge between your ISP's cable and your home router.

Why does this page show a different ISP than what I pay?

Routing databases record the legal or technical registrant of an IP block, not the company that bills you. If your ISP is a reseller, the name shown is usually the upstream provider that owns the IP range. Corporate and university networks show the institution. VPN users see the VPN operator's hosting company. In all cases, the ASN is correct even if the brand does not match your invoice.

What is an ASN?

An Autonomous System Number is a unique identifier assigned to a network that participates in BGP routing on the internet. Each ASN represents a collection of IP prefixes under common administrative control. RFC 1930 defined the original 2-byte format in 1996; RFC 6793 extended it to 4 bytes in 2012 to accommodate the growing number of networks. When you see a number like AS15169, that is Google's primary ASN.

Can I change my ISP without changing my IP?

Typically no. Your public IP is assigned by your ISP from their address block. Switch providers and you get a new IP from the new ISP's range. Static IPs from a previous ISP cannot be ported to a new one under normal circumstances. Business customers in some regions can request portable address space directly from ARIN or RIPE, which travels with the organization rather than the ISP, but this is uncommon and not available for consumer connections.

Why does my mobile carrier show a different city?

Mobile carriers route all data traffic through regional network access points before passing it to the internet backbone. The IP your device gets is assigned at that regional gateway, not at your physical location. Depending on the carrier's network topology, the gateway serving your area might be in a city hundreds of kilometers away. This is a carrier routing architecture decision, not a detection error on this page.

Related tools

The raw IP address behind your ISP is in the What Is My IP tool. Use it when you need the numeric address for firewall rules or a support ticket. DNS is separate from ISP routing; your resolver may belong to a different organization than your ISP. What Is My DNS shows which resolver is handling your queries. If you want to verify that a VPN is masking your real ISP, the VPN leak tool compares your public IP, WebRTC IP, and DNS resolver IP in one view. For the city and country associated with your IP, What Is My Location leads with geographic context instead.

Sources cited above

• RFC 1930: Guidelines for creation, selection, and registration of an Autonomous System (1996)
• RFC 6793: BGP support for 4-octet Autonomous System Number space (2012)
• Team Cymru IP-to-ASN mapping service: DNS-based BGP origin lookup
• MaxMind GeoLite2: ISP and organization name enrichment
• ARIN, RIPE NCC, APNIC, LACNIC, AFRINIC: Regional Internet Registries for WHOIS organization records

Common questions