I don't know if you get frustrated with the relatively short time that some mobile phones appear to ring before going on to Voice Mail and wished that this timescale could be extended (bag/pocket search and extract time) , but if you suffer from this problem, then here is a fix.
Note: This may not work for all phones or networks, but you can't do any harm trying..
Step 1. Key in the following into your phone *#61# then press the call/send button. This will return a telephone number and, on smartphones, the current delay time before voice mail kicks in .
Step 2. Write it down. (For Orange, I think the number would be 0793100123 for example)
Step 3. If you wanted, say, 25 seconds, before the Voice mail activated, then you would put 30 where the nn is in the following string and the telephone number from step 2 where the xxxxxxxx is.
Key in **61*xxxxxxxxx*11*nn# followed by the call/send button and it should update the delay.
For example, if I was on Orange and I wanted a 25 second delay, I would key in **61*07973100123*11*25#
If your phone reports the delay time, you can check by following step 1 again.
If it doesn't work, then 2 things to try.
Double-check that you have entered the correct number of stars and hashes or try putting the telephone number in International format (eg +44793100123 instead of 0793100123)