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Communications were once restricted to landline telephony and two copper wire-based networks, ISDN and the public switched telephone network (PSTN). The ISDN-based exchanges use primary rate interface (PRI) connections to handle video conferencing, but they can't scale for business traffic. PSTN-based exchanges are public telephone networks that use old telephone lines for communications and aren't built for high-speed internet and business communications.

Business phone systems have become central for modern corporate communications because they can scale to meet the traffic needs of simultaneous video, voice, and data. In order to add file sharing, chat, and video conferencing features, businesses need the SIP calling and trunking.

In this article, find out exactly what SIP calling is, how it differs from voice over internet protocol (VoIP), what the benefits are, and key features to look for when choosing a SIP provider.

 

What is SIP?

Session Initiation Protocol (SIP) is a cloud-based protocol that allows organizations to communicate without relying on traditional private branch exchange solutions like PRI and PSTN. With SIP, making local, long-distance, and even international calls using the internet is possible. SIP can also integrate voice, messaging, video, and even fax into communication sessions. The protocol connects you and other participants to a single channel and closes the connection when the conversation is complete.

 

What is SIP Calling?

When SIP calling is used for a video meeting or other business communications, it uses a virtual SIP trunk connection. SIP calling connects offices and their customers without using traditional landlines.

In some regards, SIP office phone systems are very similar to standard phone lines; they just require a wired connection to work. You can even wire a SIP device into a computer that isn’t turned on and still make and receive phone calls. Calling this way also grants basic features like caller ID and voicemail, and if you don’t have physical SIP phones and handsets, there are plenty of softphone solutions to use.

 

How Does SIP Calling Work?

SIP works by transmitting packets of data over the internet and utilizing a complex internet protocol to initiate and terminate SIP sessions at the appropriate time.

Let’s take a look at some of these baseline technologies to get a better idea of how SIP calling works.

 

SIP Addresses

Since SIP calling is designed to allow information to travel from one location to another, you will have to have a SIP address or an endpoint so that the message has a destination.

A SIP address can be linked to a specific individual or to a computer application that makes and receives calls like you would find in a call center. Once the call is established, the protocol also lets you know if another party enters the connection during the session, and ends the call by cutting off the connection to the address.

 

SIP Codecs

SIP packets are coded so that they are sent over the internet as audio signals. There are a few different SIP codecs, but the most common are G.711 and G.729.

G.711 is a high-quality uncompressed codec used for digital voice data. It takes up a lot of bandwidth, so you may not be able to use this codec with simultaneous SIP calls.  G.729 is used when the voice data is compressed. The quality of this message will be diminished slightly, but there’s a smaller bandwidth requirement.

 

SIP Protocols

After the files have been encoded into packets using G.711 or G.729, they are sent using two protocols: RTP and RTCP. RTP is the real-time transit protocol that sends the data using a specialized application layer specifically for audio and video data. Since this is highly specialized for these types of calls, calling and video conferencing are clear and jitter-free.

The second protocol is an extension of the first. RTCP is the RTP transport protocol, and it’s designed to provide information about the data packets being sent. The data includes packet counts, round-trip time, and the degree of jitter. Effectively, RTCP works as a quality of service (QoS) feedback technology during SIP calls.

 

The Benefits of SIP Calling

SIP calling is a technology that can be used by startups, small businesses and large contact centers for communications with consumers and between colleagues. Here are a few of the benefits of SIP calling.

 

Scalability

Traditional phone lines require extra hardware. Adding PRI lines is also expensive because PRI is only available in clusters of 23. This adds an additional 22 lines for calling and conferencing that you might not need. You will not need to purchase excess lines before you need them with SIP calling because of the option of purchasing a single line at a time from a SIP provider.

If you have a business that is located at two different addresses, you can have both buildings on the same network. This means that you will only need to use the internet to be interconnected, even if the offices are located geographically far apart. Because of this, the system will be able to be upgraded while adding new features simultaneously.

 

Cost-Effective

With SIP calling, a company can save on local and long-distance calls alone, but if international calls are made frequently, the amount that a business can save will increase drastically.

For international telephone calls, SIP offers even more cost savings because international calls are often much more expensive on a traditional phone plan. Some SIP trunk providers also have free international calling. Your business will also be able to save money by eliminating excess hardware, maintenance costs, multiple networks, and installation costs. Trunks only require an IP-enabled PBX SIP server or a VoIP gateway that connects your traditional PBX to the cloud.

 

Easy Team Collaboration

SIP trunks transmit both voice and data, so you’ll be able to incorporate it into a variety of inter-company uses like unified communications. This ties in voice calling, file sharing, instant messaging, and video calls into your company’s communications toolkit. VoIP service providers use SIP as a protocol in business phone plans since VoIP calls only work with voice data packets, the core of SIP calling.

 

Better Call Routing

SIP calling makes it easy to route to mobile phones or other workstations. This will make you more available for customers/coworkers to contact during times when you are out of the office. Call routing keeps from your phone to another employee’s extension or smartphone.

 

The Difference Between SIP Calling and VoIP Calling

SIP is often used in VoIP calling as SIP trunks act as a virtual phone line and contain multiple channels. SIP trunks and SIP protocol can be added into a VoIP system in order to allow for multiple phone lines and multimedia functionality.

Here are some of the differences between SIP and VoIP.

SIP VoIP
How it works Packet switching over the internet Packet switching over the internet
Call quality High-quality High-quality
Security Highly secure Highly secure
Pricing A fraction of the cost of traditional telephony A fraction of the cost of traditional telephony
Communication channels Voice, messaging, video, fax, and more Voice only
Integrations Easily integrates with other third party apps Cannot integrate with third party apps and software
Hardware Hardware must be SIP enabled Any hardware that can make calls over the internet (softphones, IP phones, desk phones etc.)

 

Key Features of SIP Calling

SIP calling can be used to integrate a number of features into your VoIP phone system including:

  • Call routing: Allows companies to forward calls to specific departments, agents, voicemail machines, outside phone numbers etc.
  • E-911: Enables users to connect with emergency services in the case of an emergency such as the police or fire department
  • Call recording: Enable users to record calls on-demand or set up automatic rules and notifications
  • Video conferencing: Allows users to connect in video meetings that incorporate tools such as hand raising, virtual background, screen sharing, in-meeting chat, etc.
  • IVR: Allows companies to set up call menus and call forwarding rules to route incoming calls based on caller input
  • SMS/MMS text messaging: Enables communication via text and other messaging platforms such as WhatsApp and Facebook messenger with image attachment capabilities
  • Virtual fax: Allows companies to send and receive fax over the internet without the need for a scanner or fax machine
  • Reporting+Analytics: Allows users to capture data such as call duration, abandoned calls, duration, etc. and view data in a customized report
  • AI-powered tools: These tools leverage artificial intelligence and natural language processing to transcribe and summarize calls and voicemails, provide agents with caller details, and more.
  • Self-service tools: Companies can build chatbots or voicebots to help answer common questions and perform simple tasks

 

Who Should Use SIP Calling

SIP calling reduces unnecessary spending and has better integration with unified communications platforms. SIP calling improves the collaboration efforts of globally-disparate offices and will work well in call center environments.

SIP helps provide a solution to many of the issues a business might have with their communications profile. It also delivers a strong framework for a new business to establish internet-based communications. Since Wi-Fi calling uses SIP to connect devices to PSTN and mobile networks, this technology also becomes very integral to offices that are moving towards a remote or hybrid workplace.

 

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