If you have someone working from another location other than the office such as home workers etc and the person no longer needs access to their use their VoIP phone line you can disable the users access to the line by doing the following:
1. Go to the Phone icon inside your account:
2. Click on the 'Line Summary' icon
3. Go to the particular VoIP line and click on 'Configure' as shown above.
4. Change the number that is shown inside the 'Secret' field
5. Click on 'Update' to save the changes.
By doing this the VoIP line will be unable to register successfully (as the line will re-register every few minutes) with the line credentials that have been entered into the set up of either the softphone or phone handset which means the line will fail and will be 'offline' meaning that the user will no longer be able to make or receive calls on this line.
If you wish to change the 'Secret' number but still receive calls on the line just make sure that you set up a call divert on the line so that anyone calling the VoIP number will be automatically be diverted to another active line.
Please note that the line can still be activated for another user - as you will have a new 'Secret' number to use to set up the line on another persons phone handset or softphone.