iphone 3GS - dialing a number, tapping the digits, no sound

[thermodynamic]

:(

This morning, dialing relatives, I could hear the beeps as I touched each number. This afternoon, when calling another, there were no beeps - but I could hear the rings and her voicemail picking up the call. I'm presuming she got my voicemail message as well...

I'm an iphone newbie and apart from removing a encase backup battery/shell which got returned, I've not been anywhere near the configuration.

I also checked the main volume controls and all are set to max.

What could I have unwittingly done?

Thx!!

[thermodynamic]

:o:o:o:o:o:o:o


:(

This morning, dialing relatives, I could hear the beeps as I touched each number. This afternoon, when calling another, there were no beeps - but I could hear the rings and her voicemail picking up the call. I'm presuming she got my voicemail message as well...

I'm an iphone newbie and apart from removing a encase backup battery/shell which got returned, I've not been anywhere near the configuration.

I also checked the main volume controls and all are set to max.

What could I have unwittingly done?

Thx!!