You do realize that 1) MAC addresses are universally unique (IOW, there's not another device in the entire world with the same MAC address as your Micromax's wifi or 3G/4G adapter) and 2) if your device ever ends up on the same network as the device whose MAC address you're using, a lot of places are going to know about it. (In the US, a few government agencies are among those few, since the federal law against changing MAC addresses is still on the books somewhere.) It'll also cause both devices using that MAC address to disconnect from the network.
About the only legitimate reason there's ever been for changing a MAC address was back when ISPs registered connections by MAC address and if you changed routers, and couldn't get tech support on the phone to change your MAC address in their records, you were offline until you did - or unless your new router could spoof the MAC address or your old router. (And you only did that until you could get tech support to change their login information to your new router's real MAC address.)