After WhatsApp recently cut it ties with Android 2.1 and 2.2, iOS 6 and Windows Phone 7. It had previously mentioned this move earlier in the year in a blog post. Telegram take a turn to announce that its leaving behind users running Android 2.2, Android 2.3 and 3.0 too. Android 4.0 Ice CreamSandwich is the minimum operating system version required to run Telegram's latest version.
Although not mentioned by Telegram, their motives for ending support of such old platforms are to enable the software to get more features which require a new operating system. If you are a Telegram user still running the Android older version, you can try out Telegram web from your mobile browser.