This is most likely, FALSE.
Telegram would never launch an ICO. The purpose of ICOs is to collect money but telegram is freely funded by rich people whose goal is to make quality messaging 100% free.
This is directly taken from the TELEGRAM FAQ:
Q: How are you going to make money out of this?
We believe in fast and secure messaging that is also 100% free.
Commercial companies frequently face the need to compromise their values for financial gain. This is why we made Telegram a non-commercial project. Telegram is not intended to bring revenue, it will never sell ads or accept outside investment. It also cannot be sold. We're not building a user base, we are building a messenger for the people.
Pavel Durov, who shares our vision, supplied Telegram with a generous donation through his Digital Fortress fund, so we have quite enough money for the time being. If Telegram runs out, we'll invite our users to donate or add non-essential paid options.