By default the connect applet is configured by default to ring for 30 secs before trying the next available number. 

To reduce this duration, 

1) Identify the app with the call flow that is connecting your calls.
2) Click on the 'Edit call app' on the App Bazaar -> 'Installed Apps'  section
2) Navigate to the Connect applet
3) You can now set the 'Number of seconds to ring the agent's phone before trying the next person' field to a shorter duration (say 15)
4) Click 'Save' and 'Close'