Is it just me? Or is China's mobile phone system getting ragged?

Is this just me? A year-plus ago, when I arrived in Shanghai, I marveled at the coverage and reliability of China's mobile-phone network. (Yes, I know, that's an advantage of building the system from scratch fairly recently, compared with America's patchwork system that has evolved for several decades.)

The coverage is still impressive: inside elevators, underground on the subway, on the MagLev train going 250 mph, in basement shopping malls. Any place any time, the same consistent 4-bar signal. (I'm using the China Mobile network, vs China Unicom.) And for the main purpose that Chinese mobile phones serve -- as vehicles for text messages to other mobile phones -- it still works fine.

But over the last two months, more and more often I find cruddy call quality when I use the phone to talk. Dropped connections. "Say that again, you've cut out for a while" comments. Simple garble that makes you dial again or just give up. It's like all the bad things I remember about mobile coverage back in the U.S.

Coincidence? Sign that the network has been adding new customers too fast (5 million for China Mobile last month alone)? Therefore one of many indications of strain in the Chinese infrastructure? Or just something wrong with my own phone?

I don't know, but this will be interesting to follow. I'll be watching for the next time I get a really good voice connection on my mobile phone.