Start Music On Hold

Starts music on hold playing.

You can use this action if you about to run a Step that takes some time to complete and provide no interaction with the caller.

This action works with Stop Music On Hold to give you complete control

For example you might be about to use the Send SMS message step which can take a no. of seconds to complete. 

Its generally not considered good form to leave a caller sitting in silence. A typical sequence that avoids this might be:

Play Message: Please hold for a moment whilst we send a notification
Start Music On Hold
Send SMS
Stop Music On Hold

You don't need to Start Music On Hold when sending a call to a Queue as the queue looks after playing Music on Hold itself.