Voice over Internet Protocol (VoIP) is a protocol optimized for the transmission of voice through the Internet or other packet-switched networks

An IP phone uses Voice over IP technologies allowing telephone calls to be made over an IP network such as the Internet or a private IP network instead of the ordinary public switched telephone networks (PSTN or the telephone line). This type of phone has a regular phone jack and an Ethernet jack for hookup to your home computer network.

IP phones look like ordinary landline phones or cordless phones. But with these phones, you simply switch back and forth between a regular phone jack and an Ethernet jack. If you make long-distance calls frequently, this system is a major boon to saving money. All you need is the required high-speed Internet access.

Common features of IP phones include caller ID, dialing using name ID, locally stored and network-based directories, conference calling, call park, call transfer, and call hold. You can also include applications such as weather report, attendance in school and offices, and news.

The problems with IP networks are that they are easily congested, the voice quality may not be good, or your call may even be dropped. Additionally, VoIP phones do not work as well with satellite Internet and other high-speed Internet connections, and it can be a challenge to route VoIP traffic through firewalls and address translators.

The security of IP phones is still unclear. Also, like cordless phones, your IP phone is dependent on your home’s power source.

Finally, VoIP phones have had problems dialing emergency numbers because the IP system might not be easily routed to a nearby emergency call center. Sometimes, VoIP systems may instead route emergency calls to a non-emergency phone line at the intended department.

To offset this problem, VoIP providers must support emergency services by offering an E911 emergency calling system to its customers for an additional cost. Participation in E911 is not required but has been successfully used by many VoIP services to provide physical address information to emergency service operators. One setback, however, is the diligence of the customer to keep emergency address information up to date, since the burden of responsibility is on the subscriber and not the service provider.

Other VoIP options include a “soft phone,” which is software-based, where calls can only be placed from the computer on which the “soft phone” software resides. You may be able to connect your traditional analog phones directly to a VoIP phone adapter without the need to operate a computer. The converted analog phone signal can then be connected to multiple house phones or extensions.