Telco Loan Calculator

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Telecommunication also known as Telecom, is the exchange of all types of voice, data and video transmission like signs, signals, messages, words, writings, images and sounds or information over significant distances by electronic means such as wire, radio, optical or electromagnetic systems.


It is a device which calculates number of telecom channels required to handle given telephone traffic using Extended Erlang B algorithm.

Erlang B formula

First, calculator uses Erlang B formula to calculate blocking calls fraction (call congestion) in telecommunication networks.

Formula Telco Cal

Where, A – offered traffic in erlangs
n – Number of communication channels.

This formula is not well suitable for computation systems, therefore, we use modified recursion formula:

Formula1 Telco Cal

where Formula2 Telco Cal

Extended Erlang B

Traditional Erlang B model assumes that the caller gives up call attempts after blocking, but in real life some fraction of callers retry immediately. To take into account this nuance we increase traffic volume by the given fraction of blocked calls:

Formula3 Telco Cal

where Formula4 Telco Cal– retries fraction.

Corrected offered traffic Formula5 Telco Cal again goes in Erlang B forumula, which gives new blocking calls fraction. The process repeated until stable value of corrected offered traffic is obtained.