Case Study
How a growing retail chain with 8 branches across Thailand replaced fragmented phone systems with centralized Yeastar PBX, FortiGate SD-WAN, and a single SIP Trunk — cutting inter-branch calling costs to zero.
A Thai retail chain operating 8 branches across multiple provinces with a central headquarters in Bangkok. The company opens new branches regularly and needs rapid, repeatable deployments. Staff across branches need to reach each other by extension, and customers expect a single contact number regardless of location.
Each branch had its own standalone phone system with a separate PSTN line, resulting in inconsistent call routing and no inter-branch extension dialing. Opening a new branch took weeks of phone system setup and line provisioning.
There was no centralized failover — if a branch WAN link went down, that location lost phone service entirely. IT management was fragmented, with no single view of extensions, call logs, or system health across the chain.
SIPPER deployed a centralized Yeastar P570 PBX at headquarters with FortiGate SD-WAN appliances at each branch. All branches connect to the central PBX over SD-WAN tunnels, with a single SIP Trunk handling all inbound and outbound calls.
Each branch was equipped with Yealink T31G desk phones and a FortiGate unit providing SD-WAN, firewall, and QoS in a single appliance. Dual WAN links with 4G failover were configured at every branch to ensure voice continuity.
The headquarters PBX and SIP Trunk were set up first, followed by a pilot branch to validate SD-WAN tunnel stability and voice quality. Remaining branches were rolled out using a standardized deployment kit — pre-configured FortiGate and phones shipped to each site.
New branch rollout now takes 1–3 business days from hardware arrival to full operation, including extension assignment, call routing, and failover testing.
Inter-branch calling costs were completely eliminated — all branch-to-branch and branch-to-HQ calls travel over SD-WAN at no per-minute cost. New branch rollout dropped from weeks to 1–3 days using the standardized kit.
IT now manages all extensions, call routing, and system health from a single Yeastar admin panel. The dual WAN plus 4G failover design ensures that no branch loses phone service during a primary link outage.
Yeastar P570 Cloud PBX (central), FortiGate SD-WAN appliances (per branch), Yealink T31G desk phones, SIPPER SIP Trunk (centralized), 4G failover modems, dual WAN configuration.
This case study represents a typical deployment scenario based on real project patterns.
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