SIP phones or also called as VoIP phones are connected to an IP phone system using LAN or internet. It uses SIP protocol to make a voice call over the Internet. Hence in order to make free network calls both sides need either a SIP phone adapter or softphone software and a broadband Internet connection. There are two types of SIP Phones; the hardware SIP phone and the software-based SIP phone. The first is similar to the common telephone outside, but uses purpose built hardware inside so it can receive and make calls using the internet instead of the traditional PSTN system. The second allows any computer to be used as a telephone by means of a headset with a microphone and/or a sound card. This also requires a broadband connection and connection to a VoIP provider or a SIP Server. Software SIP Phone can also run on mobile devices such as Android and iPhone.