Excellent mobile connectivity is available in Port Blair and in some parts of Havelock however as you travel to the other Islands, you may find that it is either completely absent or present but not excellent. Networks currently available here are BSNL, Airtel, Reliance and Vodafone.
Owing to the dense foliage there is poor reception of connectivity. Internet is available on Havelock and Port Blair. While connectivity in Port Blair is fairly good with fast connections, on Havelock the internet is reputed to be very slow.