Switching & numbers
| PAC | The free code (text PAC to 65075) that carries your number to a new network within 30 days |
| STAC | The same mechanism (75075) when you're dropping the number |
| Porting | The behind-the-scenes number move a PAC triggers — usually one working day |
Radio & calling
| 4G Calling / VoLTE | Voice over 4G — essential since 3G retired across 2024–25 |
| Wi-Fi Calling | Calls and texts over broadband — the thick-wall cure |
| Standalone 5G / 5G+ | 5G on its own modern core (EE leads) — snappier, smallest layer, newest handsets |
| Mast re-farming | Old spectrum reused for new tech — why maps shift yearly |
Plans & billing
| Fair-use ceiling | The cap hiding inside 'unlimited' abroad and inside some perks |
| Tethering | Sharing phone data with a laptop — capped on some unlimited generations |
| Split contract | Device credit and airtime billed separately (O2, Sky) — device payments stop at repayment |
| Spend cap | The free self-set wall against out-of-allowance surprises |
| Pounds-and-pence rule | Since January 2025, mid-contract rises must be disclosed in cash before signature |
Market & disputes
| MVNO / tenant | An operator renting masts (giffgaff, SMARTY, Sky Mobile, Tesco, iD, VOXI, Lebara, 1pMobile) |
| Deadlock letter | The network's formal 'we're done' — your immediate ombudsman ticket |
| Communications Ombudsman | The free referee whose ruling binds the network and never you |
| 7726 | The free number that forwards scam texts to fraud teams |