I am tele traffic engineer over 20 years and would like to give some information regarding to the term of busy hour traffic.
1. We need to be very careful when selecting the busy hour traffic. It may be different for local call traffic and long distance call traffic. The first thing is you need to find the actual busy hour for the service. It may be the actual busy hour traffic is much higher than the time consistant busy hour traffic. So for reality and for grade of service purpose for particular service, you need to find the actual busy hour. Do they have seasonal peak? such as for long distance call, they will have seasonal peak in Christmas and new year.
2. When you find the actual peak busy hour traffic, you need to plan for taking routine traffic measurement to define the time consistant busy hour traffic.
3. Normally we will use Erlang B for provisioning and dimensioning purpose.
4. Be careful that if you use VoIP, then some basic concept of traffic thoery will be changed.
I worked in traffic engineering department over 20 years and experience in dimersioning of digital equipment and now is learning in VoIP.