How can I detect my home phone recording to cell phone recording?

If someone is recording your home phone to their cell phone, how can i find out?

I have vtech.

Is there any phone recording device that I can judge so that I will know that there is a recording device.

Is there any chip you can put in the phone for recording?

I am not sure, but the best place I have found to sell my old cell phones is: http://www.cellitused.com