Is there any real devices to mask a female voice to that of a male over phone?

Looking for a device that can mask voices over the phone. Change a male's voice to female and vice versa...





Reason being I have received numerous prank calls throughout the day and especially so at nights. Disturbingly insane of them!


I know that these pranksters could be people I shun away from cos they are bad company. Else would be rejected hardcore suitors out for havoc or their insane lingering need to connect...





Thus would like to use the 'voice-over' ( i call that) to find out who the prankster/prankster is/are. Else I could also give them a good trashing over the phone. and ask them not to make nuisance calls again.





Wouldn't want to use my own voice over the phone and thus the need to find such a device.





Easiest way is to change my mobile no. but I rather keep the same mobile number else these pranksters might think that I am really afraid of them and need to hide... Not me!





My mobile operator advised me to make a police report which is not necessary now.Is there any real devices to mask a female voice to that of a male over phone?
There are voice changers that are used in the music industry but they are expensive!!!