So, while we wait for Reliance to upgrade us all to 4G and GSM networks, many of us will want to change to a VoLTE enabled device like a Xiaomi Redmi Note 3 or a Mi5. The good news is that these support CDMA but the bad news is that they have some small problems that are annoying at times. So, let's just do a quick run down of the problems we face when using foreign handsets on CDMA: 1. +91xxxxxxxxxx prefixed numbers don't dial. You need to prefix with zero and change your entire address book and it's a pain in the a**! 2. Call Conference. The merge option doesn't work.   Solution: 1. For +91 prefixes: Download an app in the Play Store called Prefixer (HERE). Now create a new rule. Fill up the data in the fields as follows: What this does is that it just modifies the number on the fly and dials it without the _91 prefix. It does not alter your address book.   2. For call conference: This is simple, after you have made the calls to the two parties, just go to the dialer, through the contacts app - press digit 3 and dial it. This should join the call for you.   I know these are very first world problems and most people won't even think they are problems to begin with but this helped me, so I thought I'd share. Hope this helps.