Common features of IP phones
- Caller ID
- Dialing using name/ID: This is different from dialing from your mobile call register as the user does not need to save a number to a sip phone.
- Locally stored and network-based directories
- Conference and multiparty call
- Call park
- Call transfer and call hold
- Preserving user name/ number when choosing a different service provider (not widely supported).
- Applications like weather report, Attendance in school and offices, Live news etc.
Disadvantages of IP phones
- Requires internet access to make calls outside the Local area network unless a compatible localPBX is available to handle calls to and from outside lines.
- IP Phones and the routers they connect through usually depend on mains electricity, unlike PSTNphones which are supplied with power from the telephone exchange.
- IP networks, particularly residential internet connections are easily congested. This can cause poorer voice quality or the call to be dropped completely.
- IP Phones, like other network devices can be subjected to Denial of service attacks as well as other attacks especially if the device is given a public IP address
- Due to the latency induced by protocol overhead they do not work as well on satellite internet and other high-latency internet connections.