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About VoLTEsim

About this site

VoLTEsim.co.uk is a technical reference site covering Voice over LTE (VoLTE) in depth. The site was built to address a gap: there is plenty of consumer-level “VoLTE is HD voice” content, but very little technical reference material aimed at engineers, installers, and specifiers who need to understand how VoLTE actually works, what makes a SIM VoLTE-capable, which devices support it, and what is needed to replace PSTN connections before the January 2027 deadline.

The site covers:

  • VoLTE architecture: IMS, P-CSCF, S-CSCF, QCI 1 bearers, SIP call setup
  • SIM provisioning: UICC, ISIM, IMPI/IMPU, what separates a VoLTE SIM from a data SIM
  • Device compatibility: phones, industrial routers, PSTN replacement gateways, IoT modules
  • UK context: 3G switch-off timeline, PSTN closure January 2027, Ofcom and BS EN 81-28
  • VoNR: what comes after VoLTE on 5G SA networks – see also vonr.co.uk

Author

Technical content on VoLTEsim.co.uk is written by Peter Green, an IoT and cellular connectivity specialist with over 25 years in telecoms. Peter has worked across BT infrastructure, cellular M2M, and industrial IoT connectivity. His technical writing covers LTE, eSIM and eUICC, 5G RedCap, IoT SIM provisioning, and related topics across a cluster of UK authority sites.

Technical standards

All content references 3GPP and GSMA specifications by number. Content does not cite frequency statistics or deployment figures without verifiable sources. UK operator switch-off dates are referenced from official operator communications. No content on this site is generated by AI without editorial review and technical verification.