Converting an old cordless phone into a baby monitor ?

I have an old cordless phone that I would like to convert to a monitor to hide in my out building on my car port. I would like to keep the base in my out building and tune in on my scanner in the house to know when someone is around my cars. Could someone tell me how to modify my cordless base to do this. I think the phone is in the 49 Mhz range.

If the phone doesn't have an Intercom function, then it's not simple. You could add an amplifier and speaker to the phone line jack that would convert the current modulated signal in the phone line to an audible output. This would likely require some custom circuits.