The call waiting service, available to all MTN customers, let's you have an active call and place another call on hold; you can then switch between the two as often as you'd like or finish with one call and then 'answer' the waiting call.
To activate call waiting, simply do the following:
Using call waiting
Option 1 : Put the first caller on hold and pick up the second call.
Option 2: End the first call and pick up the second call.
This service is free to all MTN customers.