Adding phones to a branch office seems simple, until calls start dropping during busy periods or audio quality degrades for no obvious reason. Most VoIP problems trace back to decisions made before a single handset is installed: how many concurrent calls the connection can support, whether latency and jitter are low enough to preserve voice quality, and whether the WAN has genuine headroom once other traffic is factored in.
Planning VoIP for branch offices: What to measure before adding more phones

