1) Wait for an expert to pop in here, but Toshiba does make analog sets with mw indicators.
2) For message waiting lamps to function on the 280, your analog station cards must be at least an RSTU2 (RSTU1 will not work)
3) If the analog phones that you currently have do have a message waiting lamp, then the Stratagy should be able to be programmed to turn the lamp on.
4) I would contact the company that did the install and get them back out to do the job correctly. If you have analog phones with MW lamps, then the tech should have set it up properly in the first place.