What are SIP Phones?

Simply put, a SIP phone is a phone that uses the Open Standard SIP to set up and manage phone calls. The actual voice is carried over an IP-based network using another Open Standard called RTP. Since these protocols are generically termed VoIP (voice over internet protocol), these phones are also sometimes called VoIP phones or VoIP clients.

SIP phones can be classified in 2 main categories:

  • Hardphones or desk phones or hardware SIP phones
  • Softphones or software SIP phones


A hardphone looks like a regular telephone, and indeed behaves as one. However, the hardware is built using network-aware, or more specifically, IP-aware components. The hardphone will connect to an IP-Network using regular Ethernet cables or using WiFi. Cordless hardphones are also available, and these devices take another industry standard cordless technology called DECT, so that the phones communicate with a base station using the DECT protocol, while the base station communicates with an IP-PBX using SIP and RTP as their transport protocols.


A softphone is quite simply what their name implies – a software program that provides telephone functionality. Again, a softphone will, just like a hardphone, use the Open Standards protocols SIP and RTP for call setup and voice delivery. Any computing device such as:

  • Desktop computers (Windows, Mac, Linux)
  • Tablets (Android, iOS)
  • Smartphones (Android, iOS)

…can run softphone programs, providing a very wide array of options from which to choose. Any computer or smart device that has a microphone and speakers (or a headset) can double up as a softphone. The only pre-requisite is an IP-based connection a 3CX system, like the one of C2 Communications.

Softphone Benefits

Using a softphone allows us to make better use of computing resources, but a more important benefit is actually the fact that it is software-based. The functionality that can be added to a softphone is limited to the software developer’s imagination, allowing him to create powerful visual tools for the user, integrate into other systems using the softphone itself as the intermediary, and so on…

The 3CX software used by C2 Communications can be used with most popular hardware SIP phones, but also comes with a completely free software-based SIP phone that showcases the benefits of a softphone, with extended functions which are not possible to achieve with a hardphone.