Mobile Signals

I just don't understand. My office building holds like nearly 3k-4k people & is one of the hot cake place that is getting developed in recent times. Still, I don't believe why cell service providers are unable to acknowledge this fact & act fast on the same. It's like most of the service providers - Airtel, Aircel, Docomo, Uninor, Vodafone, Reliance, Idea - everything is having very weak signal. I think BSNL signal will be good enough. Business - get the right product to the right people with right infrastructure to back it up...