It took 3 months and 3 attempts to port out of Idea. Make sure to pay all bills and one rental in advance + expected service tax, Also avoid outgoing calls/sms and Internet usages if you are willing to leave Idea postpaid. My rental was 99 per month and GPRS 99/- I cleared my bill and made an advance payment of 100/-(pro-rated) as I applied porting request immediately after billing date. They denied it and reason was "Payment issue."
They denied again in second attempt as I was using Internet on that number and that raised unbilled usages. 3rd month, I got it deactivated, no outgoing calls/sms were made and paid 300/- extra. They allowed porting and accounts final status was at -300/-. In words they charged 300 just to allow me to port out to another network.