It sounds almost like someone has stood 5m away from a mic and dinged a triangle, hard to notice when your custom message ends and the recording begins, I personally find.

Vodafone/Telecom etc Voicemail's make a solid "beep!" after your custom greeting message, which is great, but doesn't appear to be any ability to increase the volume with 2talk.

Anyone else notice/experience this, or even better, have a solution?