physics help.

There would be interference between the devices. i.e. the receiving device would be unable to make sense of the two conflicting data formats transmitted at the same frequencies and no communications would be possible.

As a result, the receiving mobile phone would not be able to receive and decode voice and data. Further, the remote control will not be able to operate it's partner device because the two devices are mixing up their signals.

An analogy would be like two people trying to conduct a conversation in a train station where other people are shouting nearby and the station public address system is also announcing a message.

The collective term for ensuring electrical devices operate correctly without interfering with other devices is called Electro Magnetic Compatibility (EMC).

It's the reason why government licences the radio frequency spectrum to ensure they control the rf spectrum and that there is no conflict causing equipment to stop working properly.

The military uses targeted electromagnetic frequency conflicts, as one method of 'jamming', denying or disrupting an enemies radio communications, radar and missile guidance systems.