GSM Intercom Costs: SIM-Based Door Entry Priced Honestly

Where GSM is the obvious answer

• Gates and remote entrances: the classic case — calling the house from a gate 80m away without trenching pays for the unit in groundworks saved (pairs with gate automation per that guide)
• Block retrofits: dead analogue systems replaced in a day with zero flat access — the pattern the flats cost guide centres
• Switch-off refugees: telephone-line diallers stranded by digital migration — GSM is the direct successor (the switch-off guide's prescription)
• Multi-occupancy without infrastructure: HMOs, converted houses, small offices over shops — call-the-right-phone solves what risers never existed for
• Temporary/seasonal: sites, events, lets — SIM in, working today, redeployable
• Anywhere 'just make the door call my mobile' is the actual requirement — which is most small-entrance briefs, honestly

Cost anatomy and the running-cost truth

Hardware/install anatomy: quality single-button units (AES, Videx GSM classes) £250–£500 hardware + installation/lock-interface labour → £450–£900 single dwellings; multi-button/digital-directory block panels £600–£1,500 hardware → £1,200–£3,000 installed with lock work and programming. The running line buyers must hear: SIM/service at £10–£25/month (multi-network IoT SIMs preferred — single-network SIMs in weak-coverage spots cause the 'GSM is unreliable' folklore; signal surveys precede our installs), plus call-bundle awareness on chatty blocks. Programming admin (resident number changes) rides managed portals — agents self-serve or we administer. Lifecycle: units run 7–12 years; 4G sunset horizons are the next migration to spec around (buy current-generation 4G/LTE units now, not NOS 2G/3G stock — ask the question explicitly of any quote).

GSM vs the alternatives, decided quickly

Against wired audio/video: GSM wins retrofit economics and timeline everywhere cabling is painful; loses where residents demand wall monitors or call costs over decades offend (the flats cost table maps the crossover). Against app/IP intercoms (WiFi-dependent): GSM's mobile-network independence beats premises broadband for reliability at entrances — no router reboots stranding the door; IP wins feature depth where managed networks exist (the brands guide's architecture logic). Against video doorbells: different products — doorbells serve the occupier's phone; intercom systems serve multiple parties with lock release and directory logic. The honest survey question: who answers the door, from where, on what — GSM's answer ('their phone, anywhere, today') fits more briefs than the industry's wiring habit admits.