It is possible by using the export chat function in the other apps, then share the exported files to Telegram. You can view the full instructions here.
Telegram is a free, cross-platform, instant messaging software and application service which had initially launched for iOS and Android in 2013, but only managed to track large popularity recently.
Telegram also allows for more privacy. You are able to delete messages (for both sides), groups you created, secret chats and call history for all sides, without a trace - giving the user more control.
Telegram servers don’t store information about deleted chats and call logs, so the data will disappear completely, forever, according to the app's website.
For voice chats, the user is able to see which of their groups have active voice chats as well as adjust the volume of individual participants to manage microphone levels.
The app's website states that over 100 million users joined Telegram in the month of January alone and that it has overall over 500 million monthly active users as of last month.
Other features include an improved audio player, greeting stickers and new animations for Android.
As a rival to WhatsApp, Telegram messaging apps are seeing a sudden increase in demand after larger rival WhatsApp's updated terms of service raised eyebrows on social media.