There's a really quick and easy way to extend the amount of time your phone rings for before voicemail kicks in.
Enter this code into your phone: **61*+447953222222**30# Press the call or answer key - your phone will do the rest
This will mean that your phone rings for 30 seconds before diverting to voicemail. You can alter this to ring for 5, 10, 15, 20 or 25 seconds by replacing **30# with your choice of seconds. E.g. enter **15# if you want it to ring for 15 seconds. The most you can extend it to is 30 seconds.
Using VIVID 350 Optical Fibre, Mix TV, Talk Weekends
Just another VM user trying to help out so my answers may be wrong. If you do like my answer please mark it as helpful; it may help others