Use the tool below to calculate the number telephone lines (CO) required for optimum performance of your call center operations or corporate IP PBX needs.
Enter the following data in the edit boxes:
- Number of calls per hour
Specify an approximate number of the total calls (inbound and outbound) anticipated during the busiest hour of a day in your call center or telephony network
- Average call duration
This parameter refers to the typical duration of a call when an agent (or corporate telephony user) is connected to the external party via telephone.
Click the button Calculate.
The Results table contains different amounts of phone lines depending on the frequency of call blocking, i.e. the percentage of the calls that failed to connect to the system (the caller hears a busy signal).
Calculation Model Brief
The Erlang-B traffic model was developed by the Danish scientist A.K. Erlang and initially designed for calculating call blocking values. However, over the years, this model has been successfully employed during the planning of telephony infrastructures. Today, the Erlang-B model is the primary tool used in determining the required number of telephone lines needed to connect to any PSTN network, so as to ensure optimum capacity.
To calculate the optimum number of lines (CO) required, you must estimate two parameters of your telephony network during the busiest hour of a day:
- Number of calls per hour, and
- Average call duration:
For estimating these parameters you may use log data (historical records), company telephone bills, and other sources of information.
The Erlang-B model makes some assumptions about the nature of telephone traffic and may prove inaccurate under special circumstances, such as a surge in incoming call volumes generated by television & radio advertising and other one-off promotions.
