In Real-time Communication(RTC), service minutes are calculated either by the number of users or by the number of streams. Agora calculates service minutes by the number of users.

## Approach 1: calculate by the number of users

Suppose N users talk for M minutes in a channel, the total service minutes = N * M.

• If two users talk for 10 minutes, the total service minutes are: 2 * 10 = 20.
• If five users talk for 10 minutes, the total service minutes are: 5 * 10 = 50.
• If 10 users talk for 10 minutes, the total service minutes are: 10 * 10 = 100.

In this approach, the service minutes purely depend on the number of the users in the channel, regardless of how many streams each user subscribes to.

## Approach 2: calculate by the number of streams

Suppose N users talk for M minutes in a channel, and each user subscribes to all remote streams in the channel, the total service minutes = N * (N-1) * M.

• If two users talk for 10 minutes, the total service minutes are: 2 * (2-1) * 10 = 20.
• If five users talk for 10 minutes, the total service minutes are: 5 * (5-1) * 10 = 200.
• If 10 users talk for 10 minutes, the total service minutes are: 10 * (10-1) * 10 = 900.

In this approach, if a user subscribes to multiple streams, every remote stream the user subscribes to is counted.

## Difference between the two approaches

See the table below for the difference between the two approaches:

Scenario Service minutes by the number of users Service minutes by the number of streams
Two users talk for 10 minutes. 20 minutes 20 minutes
Five users talk for 10 minutes. 50 minutes 200 minutes
10 users talk for 10 minutes. 100 minutes 900 minutes

The difference between the two approaches become greater when more people join the channel.

## Calculation approach by Agora

Agora calculates service minutes by the number of users, which is easier and more straightforward.