Solved! Go to Solution.
@JJB: As far as I'm aware you will need to speak with your network provider to increase the time it takes for your phone to ring through to voicemail. I understand you've been in touch previously, however there are no native options on the phone that can achieve this.
I'm sorry this has not worked for you, and I know how frustrating it all is only too well!!
The network operators only seem to have one code which didn't work for me!
I tried many codes from Youtube, Google, etc before I stumbled across one that worked on my phone.
I don't know why there are different codes for various Samsung phones, but if you haven't already, do a Google search and several codes come up for your particular phone. Give these a go. The best of luck!