Interpreting STL100 version numbers
I believe (but could be wrong) that Z10 STL100-1 phones cannot be upgraded (autoloaded) to the latest OS 3.3.3216 but all of STL100-2 to 4 can be. I have a couple of 2s and 4s. The microphone aperture on 2s seems to include a strip of fabric; on 4s there is a much neater integrated plastic grid architecture.
There is no difference in utility between 2s and 4s that I have been able to discern. Is it just a matter of differing (and presumably expanfdng) phone service capsbility?
Incidentally, one 2 is still cellophane wrapped unused, others are used but very well cared for. Is there any market or do all of us diehards have as many machines, and more, as we are ever going to wsnt?