SIP devices are getting to be very common now, especially with open source bundled OS offerings like Trixbox making it easy to setup your own digital or IP-PBX.
Along with the frequent installations, many (if not most) VoIP devices have available a Web GUI for their configuration, management, and report generation. These Web GUIs are often on default, meaning that the moment you install the IP phone or IP PBX, the Web GUI is immediately available on the network. And unfortunately it is also common for the username and password to have default values.
Sipflanker will help you find these SIP devices with potentially vulnerable Web GUIs in your network.
What the application does is search the range of IPs you specify, and checks if port 5060 is available. Whether open or close, port usually 5060 indicates the presence of a SIP device. Then it checks if port 80 (http) is open. The combination of an open port 80, together with port 5060, either open or closed, signals a probable SIP device with a Web GUI.
Sipflanker then proceeds to extract the website, and fingerprint the device. You can find default passwords for IP phones here.
You can download sipflanker here:
Or read more here.