New to virtual numbers, or just want to know what a term in your porting paperwork actually means? This page covers the vocabulary you'll run into most often — organized the way you'll actually encounter it: number types first, then everything related to porting and ownership, then compliance, then call routing.
Number Types
Virtual Number
A phone number that isn't tied to a physical SIM card or a fixed line at a specific address. Calls to a virtual number route over the internet to wherever you configure them to go — a mobile phone, a SIP trunk, a softphone, a different country entirely. This is the umbrella term for every number type below.
DID (Direct Inward Dialing) / DDI (Direct Dial-In)
Same thing, two regional names — DID in North America, DDI in most of the rest of the world. A standard local number tied to a specific city or area code that lets callers reach you, or a specific extension, directly.
Toll-Free Number
A number your customers can call for free — you pay for the inbound minutes instead of them. In the US/Canada this includes 800, 888, 877, 866, 855, 844, and 833 prefixes.
ITFS (International Toll-Free Number)
The toll-free equivalent for a country outside your home market. Lets customers in that country call you for free on a number that looks and feels local to them.
UIFN (Universal International Toll-Free Number)
A single toll-free number that works across multiple participating countries at once, instead of a separate ITFS number per country.
Vanity Number
A toll-free number chosen for memorability — either because it spells a word on the keypad (1-800-FLOWERS) or is simply easy to recall.
Shared Cost Number
A number type (0845, 0870, and similar formats in the UK, Australia, and parts of Europe) where the call cost is split between the caller and the receiving business, rather than being fully toll-free or fully caller-paid.
Mobile Virtual Number
Behaves like a local mobile number in its country, so customers who expect to dial a mobile-format number (rather than a landline one) can reach you naturally.
TrueLocal Number
AVOXI's 2-way local calling solution for select countries — receive calls on a local number and make outbound calls displaying that same local number, so your caller ID looks native to that market on both legs of the conversation.
Porting & Number Ownership
This is the section with the most industry jargon — most of it shows up on your LOA or in carrier correspondence, even if you never see it inside the AVOXI platform itself.
Porting (Number Transfer)
Moving an existing number from one carrier to another without losing the number itself. Regulators in most countries require carriers to support this so businesses aren't locked in.
Port-In / Port-Out
Porting a number into AVOXI from your current provider (port-in), or out of AVOXI to a different provider if you switch carriers down the line (port-out).
Losing Carrier / Gaining Carrier
Standard industry terms for the two carriers on either side of a port. The losing carrier is your current provider, giving up the number. The gaining carrier is the new provider — AVOXI, in a port-in — receiving it.
LOA (Letter of Authorization)
A signed document giving the gaining carrier permission to request your number from the losing carrier on your behalf. Almost every port requires one.
LSR (Local Service Request)
The formal order the gaining carrier submits to the losing carrier to actually start the port, once your LOA and account details have been validated. This is the industry-standard "paperwork" step that happens behind the scenes after you submit a port request.
FOC (Firm Order Confirmation)
The losing carrier's confirmation that the port has been accepted, including the scheduled cut-over date and time window. Receiving an FOC is a good sign — it means the port is on track, not stuck.
LNP (Local Number Portability)
The formal industry term (mainly used in the US/Canada) for porting non-toll-free numbers between carriers. You'll sometimes see AVOXI's or a carrier's porting team referred to as an "LNP team."
NPAC (Number Portability Administration Center)
The centralized US/Canada database that keeps track of which carrier currently owns which ported number. When your port completes, NPAC is what gets updated so every carrier in the country knows to route your number to AVOXI going forward. Toll-free numbers don't use NPAC — they transfer via a RespOrg change instead (see below).
LRN (Location Routing Number)
A 10-digit identifier tied to the carrier's switch that actually handles your number after a port. It's the technical detail NPAC updates behind the scenes — you won't typically need to reference it directly, but you may see it in carrier documentation.
PON (Port Order Number)
The reference number assigned to your specific port request — useful to have on hand if you're checking status or escalating a delay.
RespOrg (Responsible Organization)
The entity officially registered as responsible for a specific toll-free number in the industry's toll-free registry. When you port a toll-free number to AVOXI, AVOXI becomes the new RespOrg of record — this is the toll-free equivalent of an NPAC update.
Snapback
A port reversal — the number automatically routes back to the losing carrier if a port fails, is disputed, or is later found to be unauthorized. It's the industry's safety net so a number is never left unroutable.
Number Pooling
A method carriers use to allocate blocks of local numbers efficiently within an area code, instead of assigning every number to one carrier permanently. This happens at the carrier level in the background — it doesn't affect your ability to use or port a specific number.
Portability
Whether a given number — in a given country and number type — is even eligible for transfer between carriers. Not every number, in every country, is portable; some are restricted by local regulation.
Compliance & Identity
KYC (Know Your Customer)
The identity-verification documentation carriers and regulators require before activating certain number types — business registration, an authorized representative's ID, proof of address — varying by country.
CNAM (Caller ID Name)
The database lookup that displays a business or caller's name — not just the number — on the recipient's caller ID screen, where supported. Availability and setup requirements vary by country.
STIR/SHAKEN & Attestation
STIR/SHAKEN is an industry framework (primarily US-based) that cryptographically verifies a call's caller ID hasn't been spoofed, assigning it a trust "attestation" level (A, B, or C — full, partial, or gateway trust). This is part of why some legitimate calls can get flagged "Spam Likely" if the attestation chain isn't fully verified.
A2P vs. P2P (Application-to-Person vs. Person-to-Person)
A2P messaging is business-to-customer texting sent through a platform (appointment reminders, OTP codes, marketing) — this is the category AVOXI's Business SMS falls under. P2P is one person texting another directly. Carriers regulate and price these very differently, which is why business texting requires separate registration.
10DLC (10-Digit Long Code)
The US carrier framework for registering local-format numbers used for A2P business texting, so carriers can distinguish legitimate business messages from spam at scale. Toll-free numbers used for texting go through a related but separate verification process instead of 10DLC registration.
Toll Fraud (IRSF – International Revenue Sharing Fraud)
A scheme where bad actors exploit a phone system to generate a high volume of calls to premium-rate international numbers they control, generating illegitimate charges. Worth knowing the term if you ever see an unusual spike in international call activity on your account.
Call Routing & Quality
Origination
The first leg of an inbound call — from the person dialing, through their carrier, into AVOXI's network.
Termination
The second leg of that same call — from AVOXI's network out to wherever you've configured the call to go (SIP trunk, PSTN line, mobile phone).
SIP Trunk
A connection that delivers calls over the internet directly to your phone system or contact center platform — typically the most cost-effective termination method.
PSTN (Public Switched Telephone Network)
The traditional telephone network — the term you'll see when a call is forwarded to a standard landline instead of a SIP trunk or mobile number.
RPM (Rate Per Minute)
The per-minute cost of terminating a call to a specific destination. This, not the number's monthly fee, is usually what drives your overall call cost.
MOS (Mean Opinion Score)
A standardized 1–5 score measuring call quality — clarity, latency, dropped audio. AVOXI's Call Quality Insights uses MOS so you can monitor performance over time instead of relying on anecdotal reports.
PDD (Post-Dial Delay)
The time between dialing a number and hearing it start to ring or connect. Consistently high PDD is usually a sign of a routing or network issue worth investigating.
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