My cellphone's built-in battery was dead yesterday, so I sent the phone out for the repair.
I found that it is pretty troublesome to backup all the messages that was created by the App "Line" when every time the phone needs to be changed over to another one.
Although the App "Line" is very popular in Eastern Asia, and lots of people like to use it to communicate with each other no matter on life or business affairs.
But, to me, it is still not an ideal "IM (Instant Messaging)" App.
There are a lot of IM apps out there and you just have to find them, try them, and see what you like.
What Carrier do you have? I have Verizon in USA and they have a online srorage place/ app through them to save that type of thing and more either autopmatically or at certain times so you don't loose information and easy transfer to different device.
I don't use line. Some I know on are Tango, Drizzle, Line, Hangouts, Skype.
I think google has one, yahoo, dand msn/hotmail, I think.
Tillian on computer but haven't looked on smarthone.