VoIP

Traditional phone systems use circuit-switched networks — a dedicated physical path for the duration of each call. VoIP converts voice to IP packets and routes them like any other network traffic, sharing infrastructure with data.

The business case is straightforward: once you have an IP network, adding voice costs primarily the phones and a software platform, not a separate telephone infrastructure. Calls between offices over your WAN or internet connection are effectively free. International calls are dramatically cheaper.

VoIP quality depends on the network. Voice is latency and jitter sensitive — packets that arrive too late or out of sequence cause audible degradation. The requirements that make this work:

QoS — voice traffic must be prioritized over bulk data. A large file transfer sharing bandwidth with a VoIP call will degrade call quality without QoS enforcement.

Voice VLAN — IP phones belong in a dedicated VLAN, both for QoS policy application and for security isolation.

LLDP-MED — phones learn their VLAN assignment from the switch via LLDP-MED advertisement, enabling plug-and-play deployment.

PoE — IP phones are almost universally PoE-powered.

Common VoIP platforms: Microsoft Teams Phone, RingCentral, Zoom Phone, Cisco Unified Communications, 3CX. All follow the same underlying model — SIP (Session Initiation Protocol) for call setup and RTP (Real-time Transport Protocol) for audio delivery.