a) Analysts and stocks are way too optimistic on the growth prospects of the Indian mobile companies. So Bharti and RCom are trying to use their stock to buy out other companies before the tide turns south.
b) Something similar could be said for MTN. It probably is looking to use its expensive stock as currency.
c) Is their really a strategic rationale to have an pan emerging markets mobile service player? There are hardly any revenue synergies in having a Indian subscriber as well as a South African subscriber. Cost synergies will be there - one can better negotiate with equipment vendors - but Bharti is big enough on its own to squeeze 90% of the cost savings out. There will still be different country headquarters etc, so how does one get SG&A synergies?
The stock chart of Vodafone says it all - stock is today where it was in May 98. Bharti would be better served by buying Idea or Vodafone India out if they really want to do a deal - reduce competitor, gain market share etc.