As standard your phone line will go to voicemail if answered after 20 rings.
If a voicemail has been set up on your line - click here to see how to set up - you can shorten the time the phone rings before it goes to voicemail by doing the following:
1. Click on the Phone icon
2. Click on the Line Summary icon as shown below:
4. Change the 'Ring Time' drop down as shown below - for example change this to 10 rings:
5. Click Update to save.
6. Your phone should now ring for the number of seconds you have selected - after which it will go to voicemail.