SubHumanGuy schrieb:

Can any of the new scanners be modified to scan 2.4 ghz or higher?

There are some scanners (mostly -but not all- desktop models) able to
scan the 2.4Ghz range. Some up to 4 or 5 Ghz. It is not really
practicable to modify a scanner to receive on this frequency range. At
least you need extreme electronic knowledge and soldering experience on SMD.
Be sure your cordless phone has 'DECT'-standard.
If your phone transmitts a digital bitstream there is no real chance to
listen to it without some FBI/CIA/NSA equipment.