His website claims that Mouser Electronics is a "partner." *Searches on
Mouser for "Telstar" and "VoiceMax" return zero results. *Hmm. . does buying
some parts from Mouser make them a "partner." *If so, I'm a "partner" with
Mouser, too.

The dictionary defines partner as "One that is united or associated
with another or others in an activity or a sphere of common interest."
So yes, in your example... you would be a partner of Mouser.