Problem with 8 bit, 8mhz wav file output

Why in the world would I need to export an 8 bit 8 mHz wav file from Cubase 8?

Because I provide phone-hold messages and and out-going voice messages to clients, and a few of these clients have systems that require this file format.

There’s a problem with the files - - there is a constant static sound when I export. I’m recording at 16bit, 44.1khz mono, and attempting to export to 8mHz 8bit mono. The sound quality is not an issue - the constant static is.

Any thoughts? Thanks