Phone beeps during night no number registered and just wakes me up

[Soo3]

Posting for my elderly aunt during the night from time to time line  just beeps and wakes her up, she does 1471 no number registers but she goes back to sleep and happens again and again not all the time just from time to time. It's not her smoke alarms or anything else but it is her telephone line how can this be stopped from happening. Any advice appreciated. Many thanks.

[Mark39]

Does she have a cordless or battery powered phone? Some emit an intermittent beeping sound when the internal battery is running low and needs re-charging.

[Soo3]

Hi 

it can't be that as she leaves phones on the cradle so always fully charged but that for response.