How do I change the number of rings on my lg phone before it goes to voice mail

This is usually set by your network provider, so you have 2 choices.

1) Call the network Customer Service number and ask them to extend the time before it diverts.

2) Try the following network code to change it yourself:

**61*XXXXX**TT# (then send/dial)
XXXXX = The number you dial to access your voicemail (if it starts with a zero remove it)

TT = The time in seconds before diverting. The maximum value is usually 30, although some people report problems when using 30 seconds. I believe the maximum is specified by the individual network, so try different value 15 / 20 / 25 / 30.