SIP
Seven Things You Need to Know about SIP
1. What Is SIP?
SIP stands for Session Initiation Protocol and is the standard that has emerged for the control of multi-media communication over IP. In simple terms, SIP is the protocol that enables point-to-point communication sessions to be established, managed and terminated in a highly controlled manner. However, SIP is a lot more than this, its extended standards provide a whole raft of what we know as digital signalling protocol in a traditional digital telephony and enables us to deliver common and advanced PBX controls over VoIP telephony.
The standard has been developed by the Internet Engineering Task Force (IETF) who first started developing this communication protocol back in 1999.Today,SIP is the standard that every major telco, communication vendor and software company is developing to within their solutions.
2. How Does SIP Work?
SIP is a text-based protocol in a similar style to HTTP or email headers. It is a way of requesting service, communicating status and also providing enhanced information related to a session. It does not rely on the underlying protocols and as such can operate over many different types of networks and is ideally placed to act as a means of providing interconnectivity.
In layman terms, SIP is a way of communicating between processes in a client/server type model. It is a way of one SIP phone requesting to another SIP phone that a call is established between them. It is a way of asking a server where a particular user is and forthe call request to be sent to the appropriate device. It is a way for a user to elect to be unavailable and as such, calls are redirected to their voice mail. It is also a way to pass on call related data such as originating line id or number dialled.
The other key benefit of SIP is that it is not solely focused on voice but is a protocol that provides the backbone to convergence. The SIP protocol supports full media convergence supporting point-to point sessions with Voice, Video, Instant Messaging, and other applications.
3. SIP Trunks
All of the leading telcos are providing SIP trunks as a means of delivering PSTN terminations to organisations. There are significant cost savings to be made in taking up SIP Trunk options from these operators as opposed to the traditional E1/T1 terminations, as well as the benefits that are being delivered through these next generation VoIP networks. There is also a saving to be made in terms of hardware and hardware footprint. SIP trunks can be deployed with a much smaller hardware footprint than traditional E1/T1 trunks. Also, for organisations with legacy switches who need to add trunks, opting to deploy a SIP based solution negates the need to expand or upgrade these legacy switches providing the alternative of a low-cost SIP termination point.
4. Migration Path To Convergence
The thought of replacing your entire existing telephony infrastructure with a new VoIP based solution can be very daunting, especially with tight corporate budgets. SIP provides organisations with a means of layering next generation telephony management on top of existing legacy TDM based telephony, extending its capability, its life and its supportability.
SIP enables organisations to migrate to a converged next generation platform rather than having to rip out and replace their existing infrastructure. It enables you to address the most pressing issues first - provide new end-points, support a new site, increase PSTN trunks, etc. It allows you to create a road-map to convergence and then, step by step, migrate along this roadmap.
5. Interoperability
By its very nature, SIP is the next generation protocol to enable interoperability, not just between the corporate switch and the PSTN, but between the components of the existing corporate networks.SIP enables traditional DPNSS (Digital Private Networking Signalling System) trunking over leased lines to be replaced by point-to-many-point interconnectivity over IP and like with DPNSS, SIP provides that vendor-independent protocol to support interconnectivity.
Vast savings can be realised by organisations replacing existing lease line inter-connectivity and utilising low cost bandwidth over corporate WAN’s and VPN’s to deliver voice traffic between sites. With most switch vendors providing SIP compatibility, even with some of their older switches, this is a low cost way of widening and increasing the capacity of your telephony infrastructure.
6. Low Cost End Points
SIP is an open standard and by introducing this into your communications infrastructure you are avoiding the lock-in to existing vendors telephony end-points. You create for yourself greater flexibility and choice in the devices that you provide to your end users. Each of the leading telephony vendors offer a wide range of SIP handsets as well as a wide range of 3rd party SIP telephones being available.
In addition to this, your existing handsets, however basic, can be utilised with advanced SIP features being delivered through simple to use, browser based soft-phones. Such a migration enables you to significantly improve the telephony services you provide to your users while avoiding the expense of replacing hardware.
7. Remote Workers/Mobility
All organisations now face the challenge of a mobile workforce, people on the road, working from home or having the flexibility in which office/desk they work from. SIP enables you to support this flexibility by providing each of your users with the services they require regardless of location.
A SIP user can register with any device on your telephony network and automatically inherit the properties that you have defined for them. To them, a simple logon gives them complete flexibility. This also extends outside of the office. Home workers can utilise their existing VPN connections into your network to act as their gateway into your telephony network, either utilising a SIP phone at home or a softphone on their PC; they appear and act as if they are sat at a desk within one of your offices.