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Session Internet Protocol (SIP) Plays a Crucial Role in Making VoIP Calls

To understand the mechanics behind modern communication you need to know a lot of acronyms like TCP/IP ,FTP ,SMTP, POP3, IMAP, HTTP, and HTTPS.

To understand the mechanics behind modern communication you need to know a lot of acronyms from TCP/IP to FTP to SMTP to POP3 to IMAP to HTTP and HTTPS. And while that might look like alphabet soup at first glance, if you look closely, you will see the same letter, “P”, keeps coming up in every spoonful.

“P” in all those acronyms stands for “protocol”. Without these protocols, accepted standards or rules that allow different networks to communicate with each other, our digital world would be a virtual Tower of Babel.

VoIP Has its Moment During COVID-19 Pandemic

Voice over Internet Protocol (VoIP) is another technology that relies on protocols. VoIP, according to the FCC, “is a technology that allows you to make voice calls using a broadband Internet connection instead of a regular (or analog) phone line.”

Even before the COVID-19 pandemic, demand for VoIP was on the rise with Statista reporting that businesses in the United States went from less than 7 million VoIP lines in 2010 to 41.6 million lines by 2018.

The switching of phone calls from the legacy public switched telephone network (PSTN), also called plain-old-telephone (POTS), to the Internet was accelerated in the last year as Americans worked remotely during the pandemic.

Viterbi Magazine said: “In our current reality of remote work and audio and video conferencing, many of us would be utterly lost without VoIP.”

VoIP, in turn, relies on yet another protocol, Session Initiation Protocol (SIP), to help achieve the nuts and bolts of voice, video and messaging communication.

What is Session Internet Protocol (SIP)?

Session Initiation Protocol (SIP) is the de facto standard for establishing or initiating VoIP calls or communication sessions. In addition to establishing the call, SIP is also responsible for conducting or maintaining the call and then responsible for ending or terminating a real time session.

SIP is a text-based protocol like Simple Mail Transfer Protocol (SMTP) or Hypertext Transfer Protocol (HTTP).

SIP traces its roots back to 1996 when Mark Handley and Eve Schooler released their Session Invitation Protocol research paper, and Henning Schulzrinne released his Simple Conference Invitation Protocol research paper. Both papers were products of the Multiparty Multimedia Session Control (MMUSIC) working group of the Internet Engineering Task Force (IETF).

By March 1999 SIP was published by the IETF as RFC 2543. Today SIP is covered by RFC 3261.

Benefits of SIP

As a signaling protocol, SIP allows callers to locate their recipients, deliver their session effectively around the world, and then end the call.

Some of the benefits of SIP:

  • Locating and initiating sessions with call participants, regardless of their location, device they are using or network they are on.
  • Establishing not only audio sessions but also video and other multimedia.
  • Efficiently handles calls with multiple participants, allowing for them to move in and out of the conversation.
  • Adding, transferring, or dropping participants from a session.
  • Not only allows participants to agree on features for a session but can allow for features to change during the session.

To envision how SIP works to make calls, picture the ability to “dial” your email address from a phone. SIP frees up businesses, and residential customers, from being tied to traditional phone lines.

What is SIP Trunking

Of course, not all callers are on Internet-based calling systems so for VoIP to connect with those in the POTS or PSTN legacy systems, there is SIP Trunking. SIP trunking is a term SIP providers use for a service that allows business to connect their in-house IP PBX systems to the public switched telephone network.

The SIP providers, usually an Internet Telephony Service Provider (ITSP), provides their client with a pipe, called a “trunk”, that makes the connection to the PSTN.

The benefits of SIP trunking include:

  • Scalability: Lines can be added easily as they do not require physical landlines but can be delivered over internet connections.
  • Reliability: While legacy phone systems can go out in a power failure, SIP trunking can redirect calls to backup locations or smartphones automatically, keeping you in business, even in a disaster situation.
  • No Geographic Limitations: Wherever you go, if you have an Internet connection, your phone system goes along with you.
  • Cost Efficient: SIP trunking saves on your monthly bills vs. traditional phone systems.

Hosted PBX Takes Advantage of SIP

For companies that do not have their own IP PBX in place, who are starting from scratch or looking to replace traditional PBX, SIP providers can offer hosted PBX solutions. The ITSP hosts the PBX on their own servers, delivering VoIP services, including SIP trunking built-in, for a low price.

PS Lightwave offers a Hosted PBX solution that is scalable to hundreds of concurrent calls. Hosted PBX has all the features you come to expect with traditional PBX and additional enhanced features to make your business more productive.

Contact PS Lightwave today about how their Hosted PBX can help your business grow.

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PS LIGHTWAVE, a leading telecommunications service provider headquartered in Houston, Texas, provides managed Ethernet Data Circuits, Internet, private network solutions and Voice over IP (VoIP) over one of the nation’s largest facilities-based private Metropolitan Area Networks (MANs). The switched Layer 2 network, backed by 24/7/365 Network Operations Center (NOC) support, encompasses approximately 5,500 route miles and 1,400 on-net locations and connects 100+ fault-tolerant multi-gigabit Ethernet rings for built-in redundancy, security, low latency, and high-availability. At PS LIGHTWAVE Great Connections Happen Here™.

For more information, please visit or call 832-615-8000.