SIP Server Roles.

Now, we had an introduction of few important protocol used in VoIP infrastructure (using SIP). So, now lets see some of the important SIP server Roles in the SIP based form of VoIP infrastructure.

• SIP Registrar server
• SIP Proxy servers
• SIP Location servers
• SIP Redirect Servers
• SIP Conferencing Servers

We will see each of the server roles and their purpose in detail (listed above in a different post), but now lets quickly see what is a Conferencing Server and its purpose in really short form.

When a Meeting is organized the Participants does not know where their participants are and how they are connecting. The problem happens if the users are connected via different networks/at different parts of the world via different end user devices like computer, Laptop, Mobile Phone which could be Smartphone with the Softphone application installed on it or someone dialed in to the Conference (using PSTN).

Hence, in order for all these devices to support different Codecs and different Network bandwidth requirements we need a Conference servers which has the powerful codec filters and mixers. With the help of these Codec Filters and mixers, the media traffic can be disturbed to all the participants who are connected from different parts of the world using different end points.

Lets us try to understand the Conference Server purpose with a example.

Let us consider that you have organized a Meeting with 5 users connected from different part of the world. Please note, this is very interesting because imagine that, once you have 5 participants in a meeting - the speaker connected to a high speed network don't need to bother about the bandwidth requirement of person joining through phone from the Hotel room or a person joining from Laptop from Europe, or a person joining the conference in US with good bandwidth or about another person in US who is currently travelling and attending the conference on his smartphone.

The Conferencing Server will take care of the each participants devices through which they have joined and also calculated the bandwidth present at each end user's end. If the Conferencing server is not doing these tasks, then it would be Speaker's Client responsibility to perform all the calculation and determining the best codec to the used for each end point which is awful lot of task to be carried out form a user's laptop

UC Administrators

Hello and welcome to UC Administrators Blog !




In this blog, let us discuss about what is VoIP, SIP and how it works in today IT. How business are adopting SIP for their Communication platform. How it helps the business ? and How SIP works and what are all the Protocols which SIP for a successful VoIP session.


Over the last decade the Technology had grown rapidly !! No, i am not talking about the Technology in the Consumer markets (yeah we all know that iPhone, iPad is more popular and android or windows based smartphones and devices are released in the market very often) but we are trying to discuss the Enterprise Communication space.


Earlier employees (as information workers) were predominately using Emails as the formal communication. So,

• Why there is so much hype about Unified Communication and what type of Communications we are unifying?
• What are the benefits for the users and the Businesses ?

In today's world every Business tries to cut the cost of running Business. So, managers are given targets to get similar tasks done or in fact more tasks done every year with the less cost (than a previous year). With this strategy of cost cutting, the firms try to cut the cost of IT Operations cost and IT expenditure cost by adopting new technologies. Companies also adopt to new Technologies only if they are able to see tangible (like amount of money saved without have a personal trip to have a face to face interactions, less cost for getting similar features from a different vendor product) or to get intangible benefits (improvement in the service delivery, user experience).



One of those IT strategy is to adopt new technologies in Unified Communications space. By adopting new technologies, companies also save on the Physical Infrastructure cost too (we will see that shortly).
Let us have a look at how an Information worker used to work few years ago (like in the year 2005).

• a PC or a Laptop
• a Desk Phone
• a Smartphone or a Blackberry or any other PDA's

The problem for the user is, they have to check if someone tried to contacted them via e-mail, or if somebody tired to reach them on their work Phone and left a Voice Mail when they were away from the desk) or if there are any Faxes to them or to their department instead. 
So, from an end user's perspective, you have to check Voice mail, emails, faxes as soon as they reach office (part of their job). So by Unifying all these scattered information to one end user's device will make the job lot easier. From the business perspective, users spend less time on gathering information thus improving the business productivity.




So, if an office was opened in a city ten years ago, you have the office spaces which includes cubicles which have RJ 45 - LAN f / Ethernet cable for a computer  and a RJ 11 for phones. So,  here also you need to consider the wiring cost running from the Server rooms and the man hours required setup these in the user's cubicle.




My experience:
I feel it might be interesting if I share my experience here. Like any other management, my clients management wanted to improve the employee's productivity and also cut the operations cost of running IT. They started thinking about getting more details and it started from physical infrastructure. But how ? let us see that in detail.




If an office is shifted from old building to the new office space (while booking these new office space the number of cable requirements are noted and based on these details the contract is made).




In the old offices for a user you need two ports (one for Phone and one for Computer which also includes the wiring). Now if you adopt the new Unified Communications (UC) it is also saving the number of ports and the wiring to be done. For example, if a office has 1000 users you are saving 1000 ports and the man hours saved for setting up the wiring for 1000 users. So a new user will have only one LAN cable now (may be, if you invest in Wireless LAN even this can be reduced).




So in a typical scenario you have 1 user one Data port to connect the PC - so what happens to the Phone - well we can use the Soft Phone which runs on the User's computer. Also during some projects even placing Fax over IP solution (like Right Fax were done). The reason is, so that users can send or receive faxes from their Computer itself. Hence in this scenario all the communication like phone, Fax, Email and your web are all IP based. So let us see how VoIP is used in order to make a call over a IP network and how FoIP (Fax Over IP) is used to send or receive Faxes over an IP network.




So lets see about the Protocols used for VoIP (Voice over IP) and FoIP (Fax over IP) in the latter blogs.


Lets us start with VoIP,VoIP (Voice over IP) - When you think about VoIP in today's world the first thing that would come to your mind is SIP protocol.

 

SIP: SIP the Session Initiation Protocol (which works at the Application layer of the OSI Network model) and it is ONLY used for Signaling, Identifying the End points, Setting up an SIP session, Establishing an SIP session, and to Terminate a session.
This is just an introduction, we will see them in detail later, but for now, we will understand the basics. Using SIP alone will not be able to make VoIP communication. SIP works in tandem with several other protocols like

• SDP
• RTP/RTCP or SRTP/SRTCP
• Centralized Conference control Protocol (C3P)
• STUN / TURN / ICE

SDP - Session Description Protocol is an application level protocol which is used to provide more information about the SIP session to the end points. So that the end points can negotiate the Codecs, supported parameters during the time of the Session establishment phase or even during the scenario when there is a change in the network conditions (like Codec details, frame details, On Hold details).
 
RTP/RTCP or (Secure RTP/Secure SRTCP) Why we need RTP ? Well, SIP CANNOT transfer the media (Audio/Video) from one end point to the other. So, we use the protocol twins called RTP/RTCP or SRTP/SRTCP (S- Secure).

 

STUN / TURN / ICE - these methodologies will be used or sometimes all 3 together in order to find the best possible path to reach the end point, especially when user is working behind a NAT. Because if you are using NAT you will be having a Private IP and with the Private IP you will not be able to contact the beyond the local network. We all know that in order to contact some one in the internet you need a Public IP. So, in order to help the user sitting behind to find his/her own Public IP and then to find the best possible route to reach the other end point (either using the private or public IP) and to find best optimal media path to reach the end point we use STUN / TURN / ICE.

 

 

Centralized Conference control Protocol (C3P) - When it comes to Conference we need a specialized protocol called Centralized Conference Control protocol because if you are in a Conference (even with 100 participants) all the Participants should be able to hear you clearly (which is done by Conferencing servers or who should be Leader, who can attend the meeting or who can mute the audience etc.


In the next blog we will discuss about the various SIP Server Roles.