• What is SIP

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What is SIP?

Session Initiation Protocol (SIP) is a type of signalling protocol designed to mediate the exchange of encoded IP packets between enabled devices across an IP network. SIP supports the initiation, management, and termination of online communication sessions between devices (for example, IP enabled telephones and laptops) each identified by a unique IP address. 

SIP delivers two types of IP packets: 

  • Signalling IP packets - indicating an intention to start/end a communications session 
  • Media IP packets - conveying media data (e.g. audio, video, white board data)

Why is SIP important for business?

In straight forward terms, SIP enables online communication (voice, data, video) between devices. Previously, a business premises required access to an analogue copper wire network called the Public Switch Telephone Network (PSTN) to facilitate telephone calls, and access to a form of IP transport (e.g. ethernet, fibre optic) to facilitate online data exchange (e.g. email).  

Migrating all forms of communication supported by an existing analogue PSTN system (or an existing digital ISDN network, for example) to an all-IP network supported by SIP creates a centralised communication network across all forms of data exchange. Not only does this provide business leaders with a modern public image when pitching to prospective clients, but also provides a range of benefits (please see: “What are the benefits of SIP?”). 

What are the benefits of SIP?

SIP allows companies to connect to the PSTN network via an internet connection, effectively taking over the role of ISDN in VoIP. Switching to SIP technology provides a range of benefits for businesses. 

Benefits of SIP include:

  • Cost-effective IP connections (cheaper compared to ISDN lines)

    SIP provides cheaper rental costs and a more reliable alternative in terms of maintenance when compared to traditional ISDN lines.
  • Cloud management scalability - add devices to meet demand

    SIP trunking (please see below: “What is SIP trunking?”) allows multiple devices to be incorporated into the communications network, creating scalable integration.

Immediate call diversion forms part of a Disaster Recovery plan

SIP provides call diversion options (to alternative telephone systems) where available. This helps reduce any potential impact on workflow following a primary system outage.

SIP also provides certain assurances against the threat of online fraud - SIP trunking is monitored to protect against unauthorised system access. Daily data exchange limits with automatic cut-off points may also be configured, reducing the risk of losing a significant quantity of data following a cyber security breach. 

What is SIP trunking?

Telephone calls from a landline are placed via a traditional call flow management system called the Private Branch Exchange (PBS), usually found on the site of the business premises. The PBX can, however, reach capacity (a typical ISDN line may have a capacity of 30 calls, for example). Companies can retain the PBX system and increase capacity through SIP trunking.

SIP trunking allows overflow call data to be sent from the PBX system to the internet service provider for further options in directing and placing the call. Depending on the type of data transfer supported by the recipient, connectivity is continued via PSTN or SIP for landline calls, or via the recipient's router for Voice over Internet Protocol (VoIP - i.e. IP telephony). 

Further essential SIP facts:

  • Calls are sent via large internet pipes (branching from the user’s WAN) or via broadband for home workers or small offices.
  • SIP requires onsite hardware - the switches can be hybrid between ISDN30 and SIP (if the SIP failed for any reason the data would be sent via ISDN30).
  • Excellent call quality - especially where the user has QoS enabled circuits and the correct configuration of class of service (CoS) regarding routers.
  • Cheap by comparison to ISDN30.
  • More flexible for call routing and therefore Disaster Recovery (DR).
  • Easier integration with Office 365 and Skype.

What are the uses for SIP?

SIP technology is most commonly associated with Voice over Internet Protocol (VoIP) services. However, SIP supports a variety of IP based communications, including:

  • Online gaming 
  • Instant messaging (IM)
  • Video streaming (e.g. conference calls)
  • Online fax (also known as internet fax or e-fax)
  • VoIP (Voice over Internet Protocol - telephone calls over the internet)

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