An outbound service is a task that is configured for outbound CATI telephony duty (i.e. the system will call the people in the sample list), in conjunction with an outbound group (i.e. a group of agents who are assigned to work on outbound projects).
The diagram below depicts the basic components involved in outbound duty, and their interaction.

In the task properties you can set how many interviewees have to complete the survey. This is the target sample size.
In addition, you can define quotas in which you specify which type of interviewees have to be questioned. For example, imagine we want 100 interviewees to complete a survey, where 50% of them play football and 50% of them play tennis. These are quota 1 and quota 2 in the above diagram.
Quotas can also be nested. Of the 50 interviewees that play tennis, 80% (40) have to be women and 20% (10) have to be men. These groups are quota 1a and quota 1b in the diagram.
In order to reach the target sample size, it can be necessary to release a quota. For example, 100 interviewees of which 50 women and 50 men have to complete a survey. 50 women and 45 men have completed the interview. There are no more men to call. At this point there are two options: