My k550i mobile phone is generating trouble in network connectivity.I have shown this problem to SONY ERICSSON authorized service center for permanent solution.The service center has upgrade my software version and informed me that the problem has been resolved. BUT, I am facing the same issue with network connectivity.I have tried with two other brand mobile phones, to check whether my Mobile SIM may have problem, but it was not as in other mobile phone, I am not facing any network connectivity trouble. MY PHONE IS UNDER WARRANTY PERIOD... read full review »