You could try dialing ##002#. This should disable all call redirects (on busy, when missed, etc.), including those to the voicemail. It's a device independent code. Please report back if it worked for you, as I'm not sure whether it's provider dependent.
– IzzyFeb 11 '14 at 16:04
The number of rings before going to voicemail is generally set by your carrier. You should get in touch with them.
– aleFeb 11 '14 at 18:49
Older phones had Ring quantity settings for this , after the setting was made the "cell tower" (carrier) would be sent the information. There are no such settings in my phone for this either, even though voicemail forewarding is still sent out to the tower. If anyone got thier carrier to adjust the time or ring quantity please still answer this question.
– PsycogeekFeb 12 '14 at 09:38
##002#. This should disable all call redirects (on busy, when missed, etc.), including those to the voicemail. It's a device independent code. Please report back if it worked for you, as I'm not sure whether it's provider dependent. – Izzy Feb 11 '14 at 16:04