Codecs are the combination of hardware and software that converts the analog signals in a telephone set to digital form. Typically, the digital representation of the signal is shown as a series of ones and zeros, or the equivalent electrical pulses. Each one or zero is called a bit. Packets are groups of these ones and zeros. The number of bits per packet, and how long the equipment will take to transmit a packet, can vary.
Less latency means better voice quality.
How the math works Back to bandwidth calculations. Because a CMTS typically is configured for a single downstream channel and multiple upstream channels, it s easiest to see how the traffic tables are used by considering a downstream channel as an example. To do the calculations, first take the Erlangs per subscriber and multiply it by the number of subscribers to get the total Erlangs the CMTS needs to process. Telephony traffic tables can then be used to find the number of streams needed to support the calculated Erlang load at a given probability of blocking. Multiply the number of streams by the bit rate for a particular codec and packet, and you get bandwidth.