Sony Ericsson K300i

[HappyFace]

My phone only rings for 20 seconds before going over to answerphone. Can I extend the ringing to say 40 seconds (i.e loop the ring tone)?

[koster]

Yes. If you phone up your network you can cancel your voicemail altogether. Depending on your network, they might be able to change the length of time before it goes over to voicemail.

[Skids]

The length of time a phone rings before it transfers to voicemail is a non-user-definable setting on the phone. If the phone is unanswered it merely tells the network to transfer the call to your voicemail.  The length of time can only be altered by a change in the software at manufacturer level.