Recently I had a visit to my relative's house which is 2-3 kilometers away from India-Bangladesh International border.
I manually searched the mobile networks available at that area and found 4 GSM signals which are not of Indian operators, but of Bangladeshi operators - Grameenphone, Airtel BD, Bangla Link and Bangladesh Robi (BGD Robi).
This would seriously pose a severe security threat as one can make calls with Bangladeshi operators' SIM sitting on Indian soil, these calls can be untraceable by both Indian operators as well as Indian Regulatory authorities (if international SIM cards are used).
So now the question remains: are the signals usable / unusable? TT invites its users who reside near International border areas (Bangaldesh, Pakistan, Tibet & China) to share their findings and views with 1st hand feedback from near the border!