CMcadams,
Thanks for the additional details.
If you're also unable to send and receive iMessages to this contact, it is likely an issue on their end.
The first thing we'd recommend checking is if iMessage is enabled on their device. Under Settings > Messages, iMessage should be toggled on, and have either a phone number or an Apple ID email populated in the "Send & Receive" field.
If that is already toggled on, given they're company phones, ensure that there is not some sort of restriction or profile from the company preventing this contact from enabling or using iMessage. Restrictions can be checked under Settings > Screen Time > Content & Privacy Restrictions.
As to profiles, if there is a profile installed on the iPhone, his device would have an option for Settings > General > Profiles or Profiles & Device Management. That option won't show if a profile isn't installed.
If a profile is there, at that point he may need to reach out to the company to see about having it tweaked or if this is expected.
Let us know if this resolves the issue, or if you have any further questions.
Take care.