Update. On April 17, Viber announced that the service had been fully restored.

Viber users from Russia may have problems making calls in the messenger. This was reported in the official Viber account on Twitter.

The company attributed the problem to communication problems on Amazon servers.

On April 16, Russian providers began to restrict access to Telegram at the request of Roskomnadzor. The decision to block the messenger was made by the Tagansky Court of Moscow after Telegram refused to hand over the encryption keys from users' correspondence to the FSB.
On the evening of April 16, Roskomnadzor added about 800 thousand IP addresses of the Amazon hosting provider to the register of banned sites in connection with the blocking of Telegram. Prior to this, there were about 11,000 IP addresses of the company on the black list of Roskomnadzor.
In connection with the blocking of Amazon IP addresses, a number of Russian sites were blocked, in particular, Skyeng online English school, ptichka.moscow courier service and GiveMe.ru online store .

Viber reported problems with calls in Russia. This may be due to Amazon IP blocking