I am using tata docomo from the first date I have purchased a mobile but I am used their service for around 5-6 years and still using but now these past from 2 months my 3g network is not working well the signal goes up and down again and again I call their customer care they sad this is my phones problem and I had changed the phone but problem is still after some days when I meet up with my friends then I found this problem is not my phones problem they have same problem in their phone and docomo is not doing anything.