What is SIP?

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Session Initiation Protocol (SIP) is the backbone of VoIP communication, enabling users to make calls, conduct video calls, and send instant messages over the Internet. As a business owner, understanding SIP and its benefits is crucial for improving communication, reducing costs, and enhancing overall efficiency. In this comprehensive guide, we will demystify SIP, explore SIP trunking, and delve into its numerous advantages for your business.

What is SIP and How Does It Work? 

SIP, or Session Initiation Protocol, facilitates the exchange of voice, video, and instant messages over the Internet. Through a series of messages, SIP sets up and manages communication sessions, providing a seamless and rapid connection. This results in call quality being superior to traditional phone lines, owing to its flexibility, speed in adding/removing lines, call quality, and cost-effectiveness.

The SIP trunk connects your site directly to the network (the ITSP), via an IP connection which will carry out and terminate your inbound and outbound voice calls across your PBX. Your PBX can be hosted on-site or hosted remotely and you can still benefit from SIP.

Whether you’re a business owner and looking at replacing your current phone system, or just interested to find out more, read on to find out the ins and outs of SIP, and SIP trunking.

Learn more about the ISDN Phase-out

The Role of SIP Trunking: 

SIP trunking is the service that puts SIP to work on a public network. It acts as a virtual version of an analogue phone line, connecting one or multiple channels to your PBX (Private Branch Exchange). This integration enables your business to make local, long-distance, and international calls over the Internet, eliminating the need for maintaining separate data and phone networks.

If I have ISDN, Digital and Analogue infrastructure; can I use SIP?

The SIP trunk connects your site directly to the network (the ITSP), via an IP connection which will carry out and terminate your inbound and outbound voice calls across your PBX. Your PBX can be hosted on-site or hosted remotely and you can still benefit from SIP.

Learn more about Hybrid Phone Systems

Key Benefits of SIP Trunking for Your Business:

Any business with a PBX can switch to a SIP trunking service and immediately benefit from more flexible, less expensive and more resilient phone service.

There is a vast range of benefits when it comes to upgrading your phone system to SIP, let’s take a look at some of the key factors:

  1. Flexibility with Phone Numbers: SIP trunking allows easy relocation without changing your geographic number, saving costs and maintaining professionalism.
  2. Business Continuity: In the event of office relocation, SIP trunking ensures that you can quickly and cost-effectively take your phone lines with you, ensuring uninterrupted business operations.
  3. Cost Savings: With SIP, you can benefit from lower call costs, free internal calls between sites, and reduced line rental expenses, potentially saving up to 50% on line rental and 25% on call costs.
  4. No Costly Hardware Investments: SIP trunking requires no additional hardware investment, making it easy to scale your phone system with minimal expenses.
  5. Superior Call Quality: SIP calling delivers crystal-clear voice quality, ensuring your conversations are clear and uninterrupted.
  6. Scalability: SIP trunks offer seamless scalability, allowing you to add or remove lines and adjust call volume as your business needs change.
  7. Resilience: SIP trunking copes with various situations, enabling business continuity during emergencies and peak hours.
  8. Mobility: Connect your employees' mobile devices through SIP for enhanced communication and collaboration.
  9. Line Rationalization: Reduce the number of PBXs needed to maintain, while retaining control of your business phone numbers.
  10. Eliminate Maintenance Costs: Avoid costly maintenance expenses for separate data and phone networks.

SIP Call Manager: Taking SIP Further

SIP Call Manager offers advanced business continuity solutions, empowering you to manage all phone numbers and incoming calls effectively. Features include removing or redirecting phone numbers, scheduling call routing based on business hours, email alerts for missed calls, one-touch business continuity plans, hunt groups for efficient call distribution, and much more.

Some of SIP Call Manager features:

  • Remove phone numbers - Terminate any 01, 02, 03 or 08 number and control via an intuitive online portal or app
  • Redirect phone numbers - Redirect inbound calls to achieve business continuity and flexible working
  • Time / day of week routing - Schedule call routing in advance according to business hours and call handling preferences
  • Divert on busy/out of office/no answer - Maximise call handling potential and provide an improved service to the caller
  • Date routing - Set up date-specific routing in advance e.g. Bank Holidays
  • Email alert on missed call - Ensure you are notified of any unanswered/engaged calls – ideal management tool for ensuring staff productivity and following up every sales lead
  • ‘One Touch’ business continuity - Pre-build designated business continuity call plans for your Inbound number(s) with the ability to invoke/restore last active call plan instantly – immediate continuity in the event of office evacuations
  • Call whisper agent notifications – Implement announcements to be played to the call answering agent on call pick up which prompts them to answer the incoming call with an appropriate greeting.
  • Hunt Groups - Serial, random, prioritised or simultaneous hunt group enables calls to be answered by specific people or the most available person
  • Call Distribution - Serial, hunt group and percentage-based routing enables load balancing of calls across sites or teams of people
  • Call Queuing - Queue incoming calls on a destination number to assist with call handling during peak busy periods. End user configurable announcements, breakout and overflow options. Live queue stats enable effective queue management
  • Voicemail - Customise voicemail messages to prompt users to leave details for a callback
  • Advanced statistics - Advanced management information relating to call handling efficiencies; productivity, call patterns and caller behaviour. Data includes time to answer, call waiting time, call outcome and caller details


Embracing SIP and SIP trunking offers numerous advantages for your business. Its flexibility, cost savings, scalability, and superior call quality make it a superior choice for modern communication needs. By understanding and implementing SIP technologies, you can enhance your business's communication capabilities, increase efficiency, and stay ahead of the competition. Consider integrating SIP into your business phone system and experience the transformation firsthand.

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