VoIP - IP Telephony

Many consumers today are jumping on the VoIP bandwagon assuming that they are going to save money and have a reliable telephone service, I would like to explain my reasoning why I do not recommend using VoIP at this time if you need a reliable telephone service.

VoIP stands for Voice over IP. All this means to me is that your voice is encoded into small packets and delivered across an IP network (such as the Internet in most cases, even an Intranet). Most people with high-speed broadband internet connections assume they will have no problems with a 3rd Party Internet Telephony Service Provider (ITSP).

Most internet providers have their networks heavily optimized for large packet traffic instead of multiples of small packets traversing their networks. In the case of a telephone conversation using standard protocols which most ITSP's use by default (g.711 Mu-Law) you usually are sending out about 33 packets per second each with a size of 170 bytes. Every second that is roughly 6000 bytes, it does not seem like much upstream traffic to anyone. Although when you start sending that many small packets the routers and switching equipment on your ISP side really start having to work hard, instead of sending out three or four 1500 byte packets which is usually the default maximum-transmitted unit (MTU) size a packet can be.

When your ISP starts receiving this amount of traffic, quality of service (QoS) policies and queueing classes start rate-limiting and even dropping traffic causing the part you are calling, or the party calling you to sound like the call is breaking up which is usually referred to as jitter or delay.

The g.711 protocol is as close to uncompressed as it gets, after that you are at raw (signed linear) audio. Although there are several protocols out there which heavily compress your conversations and send much less traffic across the WAN/LAN endpoint you are connecting to. Even though they compress your conversation so much you still end up sending out just about as many packets per second (pps).

This is my reasoning for which I don't believe VoIP is ready for residential usage unless you are aware of the circumstances which you will have to abide by and realize when your phone starts breaking up. Many businesses use VoIP and if it is implemented correctly it will save them thousands of dollars in maintenance and upgrade costs in the future. Most businesses use dedicated private networking circuits to endpoints and direct PRI (primary rate interface, very similar to a T1 optimized for voice traffic—no bonded channels) loop back connections to a local telephone switch not requiring any traffic to traverse the internet.

I hope this makes sense and you can learn from it. But at this time internet providers are not ready to support IP telephony/VoIP across their residential circuits. Although if you are a die hard and must have it just be aware of the consequences when the high-school students come home from school to surf the internet and you have an important call to make.