IP Phones and VoIP Handsets for SIP Systems

SIP, codecs and the phone system behind the handset

An IP phone only works if it speaks your phone system's language. SIP is the common signalling standard, but check that your provider or PBX supports the model for automatic setup. Codecs decide sound quality and bandwidth: G.711 is the universal baseline, G.722 gives wideband voice, Opus adapts to the network, and G.729 saves bandwidth on slow links. A listing that names several codecs gives you room to match what the system offers. Gateways in this category connect analog phones or lines to the network and are not phones themselves.

Powering and wiring the desk phone

A second RJ45 port lets a PC share the phone's network cable, but speed matters, since a 100 Mbit port can slow the computer. PoE, listed as 802.3af or 802.3at, removes the power adapter if your switch supplies it. Wi-Fi handsets, such as those listing 802.11ac, roam the building without a cable but need good coverage. Check the screen size, the number of line keys and the headset connection, since RJ9 and USB-C ports are not interchangeable.

Questions about IP Phones and VoIP Handsets for SIP Systems

Will an IP phone work with any VoIP provider?

Most speak SIP, so they can register with many providers, but setup differs. Some providers supply their own configuration or support only certain models, so confirm the phone is listed as compatible before relying on features such as line keys.

Do I need PoE for an IP phone?

No, a power adapter works too. PoE saves a socket and a cable if your switch or injector supplies the right standard: 802.3af for most phones, 802.3at for power-hungry models with large screens and extras.

Is gigabit needed on a desk phone?

Voice needs little bandwidth, so speed does not matter for calls. It matters if a PC is plugged into the phone's second port, because a 10/100 phone caps the computer at that speed. Choose a gigabit phone in that setup.