Identify monitor type/Techmedia TMM-14M

We need to replace a monitor for a vintage phone system. The dead
monitor is a Techmedia TMM-14M that uses a 9-pin connector. Given the
system's age this could be TTL, CGA, EGA, or VGA. Any ideas, and what a
suitable replacement might be? Haven't been able to contact the company
or find adequate information on the web.

Thanks.

Mike
mtrac@onuj.com (reverse domain)