Hello Donna,
Phones by design, emphasize frequencies involved with voice recognition. That might help explain why you're able to hear voices on machines better than live voices.
I doubt that you're getting bone conduction to help hear the phone held on your hearing impaired side. Bone conduction hearing devices like the BAHA and Transear require the device to be in close contact with the skull, to effectively send vibrations through the skull for the good side to hear.. But you still could be hearing the phone on the good side to some extent when you hold the phone on the impaired side. I like to describe it as hearing something with a basketball in the way.
When they tested my hearing, they used various levels of static noise on the good side, to make sure they were testing hearing on the impaired side by itself.. By blanking out the good ear with static, the good ear was unable to assist hearing for the impaired side.
Regards,
Rob