Samsung Galaxy S II :: Extending Length Of Time Phone Rings?

My friend has an SGS2 on Virgin Mobile and he wants to extend the length of time the phone rings before going to voicemail as he often misses calls. I can't see any settings on the handset and from what I can gather it looks like it to do with the carrier, in this case Virgin Mobile? ... I also found this info... "There's a really quick and easy way to extend the amount of time your phonerings for before voicemail kicks in. The most you can extend it to is 30 seconds. All you need to do is follow theseteps:- Tap *#67# into your phone, then press the call/answer key.- Make a note of the number that's displayed, including the + symbol.- Enter the following code:**61*the number you noted down from above**30#Here's an example of how the sequence of numbers might look:**61*+44717941123456**30# This will mean that your phone rings for 30 seconds. You can alter this toring for 5, 10, 15, 20 or 25 seconds by replacing **30# with your choice ofseconds. E.g. enter **15# if you want it to ring for 15 seconds.