"You only have enough airtime for a short call, please load airtime"

What is the point of having an automated voice telling me that I "only have enough airtime for a short call, please load airtime" continuously until I run out of airtime? Usually hearing a prompt like this is enough to make me aware that I am running out of airtime, however the fact that it gets repeated until I eventually run out of airtime kind of defeats the purpose of the message.

And the worst is when you are having a call with someone and that voice starts. It hijacks the entire call, how much money have I wasted listening to that voice.

Seriously, not sure if there is a bug with the prompt, but hearing it once and letting me carry on with my call is sufficient.