Internet terms explained
Plain definitions of the acronyms and specifications that appear on business internet quotes and contracts.
What do the acronyms on a business internet quote mean?
Most of them describe one of three things: what you are buying, how well it performs, or what paperwork moves it. DIA, CIR and static IP describe the product. Latency, jitter, packet loss and contention ratio describe performance. LOA, demarc and SLA describe the process and the promises around it.
What you are buying
| Term | What it means |
|---|---|
| DIA — Dedicated Internet Access | Bandwidth reserved for you alone, symmetrical, with an uptime commitment. 500 Mbps means 500 Mbps at any hour. |
| Symmetrical | Upload speed matches download speed. Most cable and consumer plans are not symmetrical. |
| CIR — Committed Information Rate | The speed a provider commits to deliver rather than advertise. Anything above it is best effort. |
| Contention ratio | How many customers share the same capacity. A 20:1 ratio means twenty premises draw on one pool of bandwidth. |
| Static IP | A public address that does not change. Needed for inbound connections such as a VPN endpoint, mail server or camera system. |
| SIP — Session Initiation Protocol | The standard that carries phone calls over the internet. A "SIP trunk" is the line those calls travel on. |
How performance is measured
| Term | What it means | Good figure |
|---|---|---|
| Latency | Round-trip delay for data, in milliseconds. Felt as lag on calls and remote desktops. | Under 30 ms within a region |
| Jitter | Variation in latency. The usual cause of choppy or robotic voice calls. | Under 30 ms, and under 10 ms for good voice |
| Packet loss | Percentage of data that never arrives and has to be resent. | Near zero on a healthy line; voice degrades noticeably above about 1% |
| Throughput | Data actually moved per second, as opposed to the headline speed sold. | Close to the plan speed |
Paperwork and physical boundaries
| Term | What it means |
|---|---|
| SLA — Service Level Agreement | The written commitment to uptime and a target repair time, and the credits owed if those are missed. |
| LOA — Letter of Authorization | A signed document letting a new provider act on your behalf, most often to move phone numbers between providers. |
| Demarc — demarcation point | Where the provider network ends and your wiring begins. Faults on your side of it are yours to fix. |
| MTTR — Mean Time To Repair | The average or target time to restore service after a fault is reported. |
| Letter of Agency | Another name for an LOA. The two terms are used interchangeably. |
Multi-site networking
| Term | What it means | Typically used by |
|---|---|---|
| MPLS | A private provider-run network linking your sites, with traffic prioritization built in. Predictable, expensive, slow to change. | Larger multi-site organizations |
| SD-WAN | Software that bonds ordinary internet circuits into one managed network, steering traffic across whichever performs best. | Multi-site businesses replacing or supplementing MPLS |
| VPN | An encrypted tunnel across the public internet. Cheapest way to link sites, with no performance guarantee. | Small businesses and remote staff |
Terms worth checking on any quote
- The committed rate, not just the advertised maximum
- Whether the upload figure is symmetrical
- The uptime percentage and the repair target
- The setup fee, separately from the monthly price
- The contract term, and the rate once any promotion ends
Definitions are used loosely across the industry, and two providers can mean slightly different things by the same word. The meanings that bind are the ones set out in the service agreement you sign with your provider. For a side-by-side of the products themselves, see comparing connection types.
Last reviewed September 12, 2026
