Connectivity Glossary | SignalSolved

Internet types

Fiber internet (FTTH/FTTP): Internet delivered over optical fiber all the way to the home. Generally the fastest and most reliable option, often with symmetric (equal up/down) speeds. Availability is highly address-specific — fiber on your street does not guarantee fiber to your unit.
Cable internet (DOCSIS/HFC): Internet over the coaxial cable-TV network using the DOCSIS standard. Widely available in served areas with fast downloads, but uploads are usually much slower than downloads, and speeds can dip when a neighborhood is busy.
DSL: Internet over legacy copper telephone lines. Slower than cable or fiber and being retired by many telephone companies. Often the only wired option in some rural areas — for now.
Fixed wireless (FWA): Home internet beamed from a nearby tower to an antenna at your home, including carrier 5G home internet and local WISPs. Performance depends on distance, line of sight, weather, and how busy the tower is.
5G home internet: Fixed wireless home internet running over a carrier’s 5G network (e.g. T-Mobile, Verizon). Availability is capacity-gated: being in coverage does not guarantee a slot, and speeds vary with how loaded the local cell is.
Satellite internet (LEO vs GEO): Internet from orbit. Low-Earth-orbit (LEO, e.g. Starlink) has much lower latency and works well in rural areas. Geostationary (GEO, e.g. HughesNet, Viasat) is available almost everywhere but has high latency that hurts video calls and gaming.
ONT (optical network terminal): The box that ends a fiber line at your home and converts light to Ethernet. It is the boundary between your provider’s network and your own: if the ONT is not receiving light, nothing inside the house can help. What it displays varies by manufacturer and provider — there is no cable-style standard for its readout.

Mobile

MVNO: A Mobile Virtual Network Operator — a phone brand that resells one of the big carriers’ networks (Verizon, AT&T, or T-Mobile) instead of owning its own, usually at a lower price.
Deprioritization: When a cell site is congested, the carrier may serve its own postpaid customers first, slowing prepaid or MVNO traffic temporarily. It explains why a cheaper plan on the same network can feel slower at peak times.
5G bands: low-band, mid-band, mmWave: Low-band 5G travels far and penetrates buildings but is only modestly faster than LTE. Mid-band balances speed and range (the “real” 5G most people notice). mmWave is extremely fast but reaches only a short distance with little obstruction tolerance.
SOS mode (“SOS Only”, “Emergency Calls Only”): A status-bar indicator meaning your phone cannot register on your own carrier’s network but can reach some network for a 911 call — U.S. carriers must carry emergency calls from any compatible phone. Normal calls, texts, and data are down; emergency calls still work.
VoLTE (Voice over LTE): The way voice calls travel on modern U.S. networks: as data over LTE/5G rather than over the retired 2G/3G circuits. If VoLTE is off or unprovisioned, a phone can have perfect data and still fail to place calls.
Wi-Fi calling: A built-in phone feature that routes ordinary calls and texts over any internet connection instead of the cellular network — same number, no extra app. The standard free fix for indoor dead zones; requires registering an emergency (E911) address.
eSIM: A SIM that lives in the phone’s hardware and is provisioned digitally instead of on a removable card. Convenient for switching carriers and trial lines — but unlike a physical SIM, a deleted eSIM profile can only be reissued by the carrier, so never delete one as a troubleshooting step.
Signal bars vs. real signal strength (RSRP/dBm): Bars are each maker’s unstandardized summary of signal strength — two phones on the same network can show different bars at the same spot. Engineers use RSRP measured in dBm: around −80 dBm is strong, −110 dBm is fringe. Bars also say nothing about congestion, which is why five bars can still feel slow.
Modeled coverage: Carrier and FCC mobile coverage maps are computer-modeled estimates of outdoor signal, not measurements of your living room. Real-world results vary with terrain, buildings, and your specific phone.
IMSI: The subscriber identity your carrier assigns to your line and stores on the SIM. Your phone presents it when it asks to join a network; if the network has no record of it, it refuses with reject cause #2, “IMSI unknown in HLR” — the code most phones display as “SIM not provisioned”. It identifies the line, not the handset.
SIM swap: Moving a phone number onto a different SIM. Done legitimately it is how a lost or damaged card gets replaced; done by someone who has talked your carrier into it, your calls and texts are diverted to their device and your phone goes dead. Verizon notes you might not know it has happened until your phone no longer works.
NORS (Network Outage Reporting System): The FCC system through which providers must report significant outages, notifying the Commission within 120 minutes of discovering one. The filings are presumed confidential, so the regulator learns of a major outage within two hours and the public does not — which is why a carrier’s own status page, not NORS, is what a consumer can actually check.
DIRS (Disaster Information Reporting System): The FCC’s disaster-time reporting system, live only between the moment the Commission activates it for a named event and region and the moment it deactivates. While it is active, providers file daily and the FCC publishes a free Communications Status Report giving cell sites out of service by county — the only official outage data consumers can read directly.
IMEI: The serial number identifying the handset itself, as opposed to the SIM or the line. A carrier can block a specific IMEI — typically after a lost-or-stolen report — and a blocked phone is refused service with any SIM in it, while that same SIM works normally in another handset.
Port-out lock: A per-line setting that blocks transfers of your number to another carrier until you switch it off yourself. The FCC adopted a rule requiring a free lock in November 2023, but the consumer-facing paragraphs still read “[Reserved]” in the Code of Federal Regulations and compliance is not yet required — so what exists today is voluntary and carrier-specific. Ask for it by your carrier’s own product name.
Carrier settings update (carrier bundle): A configuration file written by your carrier rather than by the phone maker, versioned separately from the operating system, that sets roaming behavior, voicemail, SMS/MMS parameters and VoLTE/IMS configuration. On iPhone a mandatory one installs itself, so the absence of an update prompt does not prove you are current; on Android the equivalent configuration is rebuilt only when the SIM loads — at boot or on a SIM swap.
IMS entitlement (GSMA TS.43): The server-side check that decides whether your line may use VoLTE, Wi-Fi calling and SMS over IP. Your phone queries the carrier’s entitlement server automatically, with no credentials you type. These are not simply local toggles: if the carrier’s record of your device is stale, the features stay off no matter what you reset on the phone.
Baseband / modem firmware: The software running on the phone’s cellular radio — a separate subsystem from the operating system, with its own version. On a normal phone it ships inside the system image and there is no Settings control to choose a version, which makes it a layer to stop chasing rather than one to act on.
Signal booster (bidirectional amplifier): A bidirectional amplifier that receives your carrier’s licensed signal outdoors, raises its power and re-radiates it indoors — and does the reverse for your phone. It holds no license of its own: 47 CFR 20.21 authorizes a consumer booster under your carrier’s license, so you must get that carrier’s consent and register the device before switching it on. It amplifies what already reaches your building and cannot create signal where none exists.
Femtocell (carrier network extender): A small carrier-supplied base station that carries your calls and data over your home internet connection instead of over the air. The FCC excluded femtocells from its signal-booster rules in 2013, and the practical distinction follows from that: a booster needs usable outdoor cell signal, a femtocell needs internet.

Geography & data

ZIP code vs. address: A ZIP code is a USPS mail-delivery route construct, not a precise service boundary. Home internet availability is address-specific, so two neighbors in the same ZIP can have different options. Use ZIP/area results to explore, then verify your exact address.
ZCTA: A ZIP Code Tabulation Area — the Census Bureau’s area-based approximation of a USPS ZIP code. It’s useful for area summaries but is an approximation, not an exact ZIP boundary.
Broadband Serviceable Location (the “Fabric”): The FCC’s national dataset of locations where fixed broadband can be installed, used as the denominator for the National Broadband Map. The underlying location data is licensed, which affects how non-providers may use it.
Broadband Data Collection (BDC): The FCC program that collects fixed and mobile availability data from providers twice a year and publishes it as the National Broadband Map. Providers file for as-of dates of June 30 and December 31, about two months after each date, so the map is a periodic snapshot of self-reported claims rather than a live feed.
As-of date: The snapshot date a broadband availability filing describes — June 30 or December 31 for the FCC’s Broadband Data Collection. A listing on the National Broadband Map is a claim about its as-of date, not about today: the filing deadline falls about two months after it, and publication to the map comes later still.

General

Availability vs. coverage: “Coverage” means a network’s signal reaches an area (common for cell service). “Availability” means you can actually order and get service at a specific location (common for home internet). A street can be “covered” yet a particular home not “serviceable.”
Latency: The delay (in milliseconds) for data to make a round trip. Low latency matters for video calls, gaming, and responsiveness — often more noticeable day-to-day than raw download speed.
Symmetric speed: When upload speed equals download speed — common on fiber. Helpful for video calls, large uploads, and working from home. Cable and most wireless options are asymmetric (slower up).
BEAD: The federal Broadband Equity, Access, and Deployment program — a multi-billion-dollar effort to fund broadband expansion through state programs. Useful context for where service may improve, not a guarantee of availability at your address today.
Bufferbloat: Latency that appears only when the connection is busy. Oversized queues at the bottleneck fill during a download or upload and every packet behind them waits, so a line can measure fast and still break video calls. Modern active queue management (for example FQ-CoDel) fights it by keeping queues short rather than by adding speed.
Latency under load (working latency): Latency measured while the connection is busy — the FCC’s own name for it is “working latency”. Idle ping is not a good predictor of how a network behaves in real use, so this is the number that tracks whether video calls hold together. Measure it by rerunning a latency test during a large upload or download.
Jitter: Variation in packet delay — how much the gap between arriving packets wobbles. The receiving end absorbs it in a de-jitter buffer, which converts jitter into either extra delay or, for packets that arrive after their play-out time, discarded audio that behaves exactly like packet loss. It breaks live calls long before bandwidth does.
Packet loss: The share of sent packets that never reach their destination. The FCC’s Measuring Broadband America report bands consumer loss at up to 0.4%, 0.4–1% and over 1%, and calls 1% the commonly accepted point where highly interactive applications such as VoIP degrade significantly — while noting that a few tenths of a percent is common and usually unnoticeable.
CGNAT (carrier-grade NAT): When an internet provider shares one public IPv4 address among many subscribers and does the address translation on its own equipment, so your router never holds a public address. Browsing, streaming and video calls are unaffected; port forwarding and anything else needing an unsolicited inbound connection stops working.
Shared Address Space (100.64.0.0/10): The IPv4 range reserved by RFC 6598 to number the link between a carrier-grade NAT and customer equipment. It is not globally routable, so a router WAN address in this range confirms CGNAT — but providers are not required to use it, so its absence does not rule CGNAT out.
Port forwarding: A router rule that sends unsolicited inbound connections on a chosen port to one device on your network — the usual way to reach a camera, NAS or game server from outside. It is an inbound-only concept, and it has no effect when your router does not hold a public IP address.
Broadband consumer label: The FCC-mandated disclosure every internet provider must display for each plan at the point of sale, listing price, fees, data allowance, contract terms, typical upload and download speeds and typical latency. If you already subscribe, your current plan’s label is in your online account portal — it is the only place the provider states a speed number in writing.
Typical speed (broadband label): The upload and download figures a provider prints on its broadband label. The FCC has not defined a statistic behind “typical”: a fixed provider may base it on Measuring Broadband America results, the MBA methodology, its own internal testing, consumer speed test data or third-party data. It is not a guaranteed floor.
Provisioned speed: The rate actually configured on your line at the provider’s equipment, as distinct from the advertised tier name. A wired result that parks at the same ceiling all day, on two servers and two days, usually points here — which is why asking a provider for the provisioned rate on your account is a more answerable question than “why am I slow?”

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