I guess Airtel already has the sanity check in place but people don't wanna digest it. They would escalate it to higher authorities to put pressure for the VDSL installation. They use the loop length metrics and anything beyond 700m doesn't qualify for a 40mbps plan for now.Recently i downgrade VDSL TO ADSL which is technically impossible. after many complaints of link drop even after changing 777vr to dlink dsl 224. in my experience it vdsl is not good if your airtel exchange is away 1 km from your house. after mailing to Airtel superior official they agreed to change vdsl to adsl. but guys they changed my number and they assure they will revert it within someday. so if any of you are thinking to change adsl to vdsl than think twice you can not downgrade easily and if you it will cause you many trouble. vdsl is good if u live nearby of exchange.