A softphone (software telephone) is an application program that enables voice over Internet Protocol (VoIP) telephone calls from computing devices. In the enterprise, softphones are sometimes referred to as soft clients.
Most softphone applications work in conjunction with a headset and microphone, a specialized VoIP phone (sometimes called a hardphone) or by using a device called an analog telephone adaptor (such as magicJack) which enables VoIP calling from a standard telephone handset.Content Continues Below
Although softphones are most often associated with mobile or home users, office workers are also choosing to use softphones as a convenient replacement for traditional desk phones. This can be problematic for network administrators because the traffic generated by softphones has the potential to flood a network.
In many cases, the network management system cannot differentiate traffic generated by a softphone from traffic generaged by other software applications. To complicate things, sometimes IP phones use the same protocols as softphones and compete with each other for bandwidth.