[entwisi]

Posted via Mobile Device
Not many phones will ring indefinately till you respond but if it will use mp3 as a ringtone then you can easily make a 10 minute one of a tone repeating.
An old siemans phone i had had some lights on its side that would flash untill you acknowledged the message. It was very useful to see quickly he you had missed a call or text.

One thing to your daughter though is that if she wants an instantaneous response she should call as sms cannot be guaranteed delivery in any specific timeframe.