One of the big issues when starting to set up a security system is the infrastructure (cabling), you need one for the signal, one for the power etc.
An IP camera integrates power, video, audio, PTZ (Pan, tilt and Zoom) control and I/O in a single cable. That means cost savings, increased functionality and vast integration potential. With an analog PTZ camera, you need a separate cable to control the pan, tilt and zoom functions. If you add audio, you need yet another cable. Together with the power and video cables, this adds up to costly and inflexible camera infrastructure.
An IP camera not only requires less cabling; it also offers rich integration possibilities. By using the input or output ports on your camera, you can enable entrance control with or without the supervision of an operator. With built-in two-way audio, an operator can communicate verbally with a person standing in front of the camera. The camera can also use audio for detection, and trigger alarms or recordings.
http://pc-tec.co.uk/ sell a range of IP Cameras that can either replace your existing analogue system or help you start up your first IP based security netowk.