Originally Posted by
travelinmanS
This has been an issue as long as I can remember in China. In short the connectivitity of both Mobile and Unicom is not that good. Along with creepingly slow internet speeds this is just something that those of us who live in China have learned to live with.
It seems like he was mainly complaining about missed handoffs while driving along 4th Ring in Bj. Maybe I too am conditioned to this stuff, but the idea of trying to make a VoIP in that situation strikes me as crazy...though not as crazy as doing the same on a train that's traveling 300 kph (something I have actually witnessed myself, believe it or not).
Regarding Mobile v Unicom and other theories introduced by the OP, IME Mobile is slightly better on the whole (especially in elevators and parking garages), but Unicom blows them away in many cities. The networks are what they are, and in spite of minor annoyances, are pretty impressive on the whole.