What Is VoIP?
VoIP stands for Voice over IP or voice over Internet Protocol. It is also known as IP telephony. VoIP is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol networks.
The terms Internet telephony, broadband telephony, and broadband phone service specifically refer to the provisioning of communications services (voice, voice messaging, fax, SMS, etc.) over the Internet instead of through the public switched telephone network (PSTN), also called plain old telephone service (POTS).
How Does VoIP Work?
The principles involved in originating VoIP telephone calls are similar to traditional digital telephony. They involve signaling, channel setup, digitization of the analog voice signals, as well as encoding. Instead of being delivered over a circuit-switched network, the digital information is packetized. Transmission occurs as IP packets over a packet-switched network.
IP packets transfer media streams relying on special media delivery protocols that encode audio and video with audio codecs and video codecs. A lot of codecs exist that optimize the media stream based on application requirements and network bandwidth. Some implementations rely on compressed speech and narrowband while others support high-fidelity stereo codecs.
Protocols of VoIP
VoIP has been implemented with proprietary protocols and protocols based on open standards in applications including VoIP phones, mobile apps, as well as web-based communications.
The VoIP protocols are the following:
- Session Initiation Protocol (SIP)
- Session Description Protocol (SDP)
- 323
- 248
- 711
- 729
- Media Gateway Control Protocol (MGCP)
- Real-Time Transport Protocol (RTP)
- Real-Time Transport Control Protocol (RTCP)
- Secure Real-Time Transport Protocol (SRTP)
- Inter-Asterisk eXchange (IAX)
- Extensible Messaging and Presence Protocol (XMPP)
- Jingle
- Skype protocol
- Skinny
It requires many functions to implement VoIP communication. Some of the above protocols have multiple functions while others perform only a few and they must be used in concert. The functions are below.
- Network and transport
- Session management
- Signaling
- Media
- Media description
- Security
- Quality of service
VoIP’s Pros and Cons
Finally, let’s see what are the benefits and shortcomings of VoIP.
Advantages of VoIP
- Access for remote workers.
- Added functions compared with a traditional phone.
- Low cost.
- Avoid paying for both a broadband connection and a traditional telephone.
- Low international rates.
- High quality.
- Smoother connection than an analog signal.
Disadvantages of VoIP
- High-speed network connection requirement.
- Unavailability during power outages.
- Not all VoIP services may connect to emergency services directly through 9-1-1.
- Lack of directory assistance or white page listings depending on the VoIP service.
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About The Author
Position: Columnist
Helen Graduated from university in 2014 and started working as a tech editor in the same year. Her articles focus on video creation, editing, and conversion. She also has a good knowledge of disk management and data backup & recovery. Through an in-depth exploration of computer technology, Helen has successfully helped thousands of users solve their annoying problems.