Multi-Branch VoIP Telephony System

The client needed a single coherent phone system across multiple offices in the same city — staff should reach any colleague by dialling a simple internal extension, regardless of which branch they're in. Budget was strict: no full hardware refresh, no new cabling. Existing analog handsets and copper wiring had to stay in service.

Deployed Grandstream UCM PBX as the central call controller managing a single, planned extension number scheme across all branches. Grandstream ATA (IP-to-Analog) converter switches were installed at each site, allowing the existing analog handsets to register as SIP endpoints over the current copper wiring — no rewiring, no hardware replacement. New office blocks that needed additional capacity received Grandstream IP phones registered directly over the LAN. All branches are interconnected via VPN tunnels, through which internal voice traffic routes transparently. A carefully planned extension range per branch eliminated any numbering conflicts across the network.

Every branch now operates on a single unified dial plan. Staff dial internal extensions identically whether they're calling the next desk or another location across the city. Legacy infrastructure — analog phones, existing wiring, networking backbone — was preserved entirely, with IP phone sets introduced only where new extensions were actually required. The rollout was completed within budget, with zero disruption to ongoing operations.