Now, we need to talk about how those devices communicate. So when you make a phone call from one person to another person, how is that communication done? Well, Voice over IP communication uses protocols. So you probably know of TCP/IP or Apple uses Bonjour or NetBIOS, etc. Well, Voice over IP uses protocols in order for the communications to happen. So this is just a network language. Now, the standard protocol that I would say you should try to buy system that use is something called SIP. SIP stands for Session Initiated Protocol. So this is the ratified protocol that lots and lots and lots of companies use. So you can buy Cisco SIP phones. You can buy Polycom SIP phones. You can buy Asterisk SIP phones. So SIP is a protocol that lots and lots and lots of vendors have implemented.
So what I like in my little world is I can buy a Voice over IP server from one manufacturer and I can buy SIP phones from other manufacturers. So if I want really expensive SIP phones, I would buy Cisco SIP phones. If I want really cheap SIP phones, I would buy Linksys SIP phones. Basically whatever my budget allows, is what I can afford. So this is the protocol. It uses SIP. SIP resides on top of TCP/IP. This is actually an application layer networking communication so this can ride on TCP/IP. This can ride on UDP. This can ride on some other protocols. So this is actually ñ itís a networking protocol but it resides above TCP/IP. So SIP is the basic communication that like I say, the Voice over IP servers use, the telephones use, etc. This is how they talk to each other.
Now, why I say SIP is important? SIP. SIP. SIP. Have you heard me say SIP before? SIP is very important and you should buy systems that use SIP as the protocol. Here is the reason why. It is because some of the major manufacturers of telephone systems, they donít really like open source. If you buy an Avaya phone system, they want you to buy Avaya. If you buy a Nortel system, they want you to buy Nortel phones. Avaya doesnít want you to buy an Avaya system and then Cisco phones or an Avaya system and Linksys phones. Avaya wants to sell you both the telephone system and all phones, the call boxes, etc that go with it. OK. Itís a fine business practice for them, but I hate it.
The way they are able to make this happen is they have their own proprietary protocols that nobody else can use. So donít quote me or donít sue me if youíre from Avaya. But the last time I was looking at Avaya phone systems, like I say, back in the day, I was certified 90 hours of certification on Avaya phone systems. I think Avaya phone systems are just the catís meow, they are very high quality, they are very basically user-friendly, etc. When I went to buy Voice over IP systems for my clients, I found out that they only use proprietary protocols now. So that kind of killed it for me. Iíve never used an Avaya phone system again. Why? Because if you buy an Avaya Voice over IP PBX or Voice over IP server, you can only buy Avaya phones to communicate with it because Avaya doesnít license out this protocol just willy-nilly. Again, they want you to buy the phone system and the phones all from them. No, I think thatís a bunch of garbage.
Thatís the other reason why I was just talking about the gateways and for Skype, Skype uses a proprietary protocol. So if you use the Skype service, you canít go out and buy just any willy-nilly Voice over IP phone to connect to the Skype service. That phone has to have the Skype protocol built into it. Again, thatís why I like SIP lots and lots and lots and lots and lots and lots and lots and lots of manufacturers build staff for SIP. And like I say, I just think itís the future and if you buy something non-SIP I just think thatís kind of dumb.
The nice part with SIP is whatís good for you as a consultant or you as a business person, Iíve seen this. Since Cisco deals with SIP and open source Voice over IP servers deal with SIP, I have seen fellow consultants where what they will do for clients, if clients want to seem prestigious, if they want to seem more important than their bank account actually allows, what the consultants will do is they will go out and they will buy Cisco SIP Voice over IP phones and then have those phones connect back to a free open source Voice over IP server. So it looks like they have this really expensive fancy Cisco system, when really all those Cisco phones connect back to a little $400 computer sitting in the back room closet somewhere.
So this is something that you can do that makes SIP nice. You can have Cisco call manager connected to the Linksys phones. You can have Cisco phones connected to the Asterisk. Since SIP is the networking protocol that allows all these devices and Voice over IP servers to communicate, you can mix and match at will. So thatís very important. Like I say, Nortel, Avaya, a lot of the old fashioned telephone manufacturers use proprietary protocols and Iím telling you itís a bad, bad, bad, bad, bad, bad, bad, bad idea to use those because you can either use stuff from everybody or the proprietary stuff.
Now, weíve talked that all these Voice over IP devices and Voice over IP server use a protocol to talk to each other. So this isnít TCP/IP. This is either SIP or itís a proprietary Skype protocol or proprietary Avaya protocol but they all use a protocol in order to communicate to the server and to other devices on the network.