As we all know, Airtel no longer supports the equipment that it gives you. So if your modem gets spoilt you better buy a new one. You could buy the exact same one as they gave you, but it is much nicer to buy a much nicer one - with integrated wifi and modem capacity, as well as a capability to use EWAN (for Tikona) or 3G internet.
Which is why I went with the TP-Link 8968ND. I bought it for a fairly cheap 2300 rupees. Try to get Version 2 of the hardware which will enable you to have 5dbi antennas for increased range - however this router does have replaceable antennas, so you could upgrade them later on.
The screenshots below show the configuration that must be set in for the broadband and IPTV to work (make sure you connect the IPTV cable to the port that you have earmarked for IPTV).