Help · Jargon buster

PlainEnglish.

Every acronym we throw around, defined in one sentence.

Telecom is built on three-letter acronyms layered on three-letter acronyms. This is the plain-English version — what each term means, why it matters, and which Giant page goes deeper on it. Skip the jargon, get the gist. Specific question? Search the whole site or ring us.

A

ADSLAsymmetric Digital Subscriber Line: Old-style broadband over a full copper pair. Up to 24 Mbps download, 1 Mbps upload. Being phased out — see PSTN switch-off.

B

BBUBattery Back-Up Unit: A small UPS that keeps a digital phone working in a power cut. Free for vulnerable customers under Ofcom GC C5; £4.99/mo add-on otherwise.
BGPBorder Gateway Protocol: The internet's routing protocol — how networks tell each other which IP ranges they're responsible for. Wholesale customers can have us announce their BGP routes.

D

DDIDirect Dial-In: A unique inbound phone number that rings a specific extension, not the main switchboard. Standard on VoiceCloud.

E

eSIMEmbedded SIM: A SIM that lives in software on the phone — no physical card. Activated by scanning a QR code; live in ~90 seconds.
Ethernet: Either the network protocol used for wired connections, or a 'leased line' product where Giant deploys a dedicated business-grade fibre to the premises (no contention, hard SLA).

F

FTTCFibre To The Cabinet: Fibre runs to the green street cabinet, copper for the final stretch into your home. Up to 80 Mbps down / 20 Mbps up. Being replaced by FTTP as Openreach lights up new postcodes. See also FTTP.
FTTPFibre To The Premises: Full fibre — glass cable all the way into your home. Speeds 100 Mbps to 8 Gbps symmetric depending on the wholesale carrier. Every Giant residential broadband plan is FTTP where available.

G

Giga Boost: Giant-specific — temporarily uncap a residential line for a download-heavy evening (big game patches, OS updates). Self-service via the customer portal, no charge. Available on selected packages.

I

ISDNIntegrated Services Digital Network: Pre-internet business voice technology over copper. Off-sale since 2025, fully switched off January 2027. Migrations land on VoIP.
ISPInternet Service Provider: Companies that sell broadband to end customers. Giant is an independent UK ISP.

L

L2TPLayer 2 Tunnelling Protocol: Wholesale protocol that hands end-customer broadband sessions to a reseller's gateway so the reseller controls IP, brand, and routing. Common for white-label ISPs.
LNSL2TP Network Server: The reseller-side device that terminates L2TP tunnels from Giant's wholesale platform. Mikrotik / Cisco / Juniper / open-source Linux all work. See also L2TP.

M

Mbps / Gbps: Megabits and Gigabits per second — the bandwidth units used in broadband. 1 Gbps = 1,000 Mbps. Note bits, not bytes — divide by 8 for download speeds in MB/s.
MNO / MVNOMobile Network Operator / Mobile Virtual Network Operator: MNO = owns the masts (EE, O2, Vodafone, Three in the UK). MVNO = rides someone else's masts under a different brand. Giant Mobile is an MVNO.

O

OTSOne Touch Switch: Ofcom rule (12 Sep 2024) requiring the new broadband provider to handle the whole switch — old provider notified, cutover scheduled, no double-billing. We do this automatically.

P

PACPorting Authorisation Code: Text PAC to 65075 from a mobile to get the code that lets you take your number to a new carrier. Free, returned in seconds, valid 30 days.
Port-in / port-out: Moving a phone number between providers. Free for mobile; £12 ex VAT per number for VoIP / landline. Number stays the same.
PSTNPublic Switched Telephone Network: The traditional analogue voice network running over copper. Being switched off nationally by January 2027. Replacement is digital voice (VoIP) over your broadband.

Q

QoSQuality of Service: Network-level traffic prioritisation — giving voice or gaming packets head-of-queue treatment. We don't throttle or QoS residential traffic at the ISP level.

S

SIPSession Initiation Protocol: The protocol VoIP uses to set up calls. Most modern desk-phones, softphones and PBXs speak SIP.
SIP-to-SIM: Giant-specific — attach a VoiceCloud extension to a real mobile SIM. The business DDI rings the mobile over the cellular voice channel (not over data, not via an app).
SoGEASingle Order Generic Ethernet Access: FTTC broadband without the bundled analogue phone line. Used during PSTN migration when a customer needs broadband but doesn't want the legacy voice channel.
STACService Termination Authorisation Code: Like PAC but for cancelling a mobile without porting the number. Text STAC to 75075. Free, instant.
Symmetric: Upload speed equals download speed. Standard on full fibre (FTTP) tiers from CityFibre / Netomnia / LCR Connect. Important for streaming, video calls, file sync. See also FTTP.

U

UPRNUnique Property Reference Number: A national ID for every UK property. Used by Ofcom's coverage data and by Openreach's order systems. We pull coverage by postcode and aggregate per UPRN.

V

VoIPVoice over Internet Protocol: Phone calls carried as data over your broadband. Replaces analogue PSTN. Residential = Giant Home Phone. Business = VoiceCloud.
VoLTEVoice over LTE: Mobile calls carried over 4G instead of the older 2G/3G voice channel. HD-quality, faster call-connect, lower latency. Default on every modern phone.

W

WiFi calling: Your mobile makes / receives calls and texts over your home WiFi when cell signal is weak. Same number, same dial. Works on Giant SIMs across all major networks.

X

XGS-PON10-Gigabit-capable Symmetric Passive Optical Network: The latest generation of full-fibre access technology. Symmetric 10 Gbps per shared fibre. Our fastest full-fibre network runs XGS-PON — that's what delivers our 8 Gbps tier.

Related help

All help topics

Pair withOne Touch Switch·PSTN switch-off·Number porting·Search the site

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