Setting up freepbx to music on hold

Hello everybody

I am a new freepbx + asterisk 1.4 user

I use freepbx 2.5.2 to setting up Asterisk and now I need to know the best way for creating the next scenario:
I have a linksys phone with 6 lines, its extension is 55510.
I have an agent who listens on 55510.

When people phone 55510 extension, for example after the tird tone, if the agent doesn’t take it, I need music on hold play while caller is waiting.
How can i do that with FreePBX?

Thank you in advance

Nick Ohn

The only setting is by amount of time in seconds. It doesn’t count the number of rings.