This list of vendors is vastly incomplete. These are just some of the companies whose products and/or services my readers, clients, and I have been usually satisfied with.
A longer list of vendors and other UNIX Serial Port information can be found on our WWW page at the following URL
If you have had a happy experience with other vendors of serial-port-based products for Sun systems, send me the info and I'll include them in this list.
Companies, their products, and their support staffs change regularly, so your “satisfaction mileage” may vary. (I don't receive any money or special favors from any of these folks, nor would I consider it. I'm just a picky consumer, like you.)