AT&T, as Bell Labs, was a phone company that created the first working version of the transistor, a concept invented and patented by Julius Lilienfeld twenty years earlier.
But they were at the time, a technology company. Technology isn't defined by silicon and code, but by the fact that a company grows by inventing new things. Google may be on track to becoming an advertising company, but they seem damn resistant to the idea given how many of their new businesses they're burning through to find new revenue.
20% time is mostly used for side projects which aren't about coding or products anymore. But back in the day most new things Google was making came out of it.
It doesn't look like Gmail came out of 20% time, Paul Buchheit was asked to work on it so it looks like it was an assigned project not a spare time thing, and Google Docs was an acquisition (Writely).