Financial Tribune- Telegram messenger, the most popular communications app in Iran, launched its voice calling service on April 13, however, according to a new tweet by the company�s founder Pavel Durov the new feature is being blocked.

Durov wrote his personal authenticated account, � Yes, we have activated calls for our users in Iran, but Iranian operators started to filter them. I think you should complain to them.�

Following Durov�s tweet, the public relations department of MCI (Hamrah-e Avval) � Iran�s oldest and largest mobile operator � announced the company has nothing to do with blocking any service.

Local technology news agency CITNA originally reported the launch of the service on Friday.

According to the report, users should first upgrade the application to its latest version using Google Play (for Android users) or App Store (for iOS users). The service is not yet available for Windows Phone users.

However, according to tests by users of the app, no one was able to connect to each other using 3/4G connections.

According to the tests the phone rings, but when the user answers the call, the application just says �connecting�.

Eghtesad Online, a popular economic news website on its Telegram channel earlier reported that the problem was due to Client-Server Overuse. This happens when too many people on a network use a service on an application at the same time than the servers of the company offering the service can support.

Later on the service was available according to our own tests.

Irancell also denied blocking Telegram's voice calling service, later in a tweet.

@amireslamdoust @nima The problem occured in Telegram voice service was not related to MTN Irancell


� MTN Irancell-??????? (@irancell) April 14, 2017
Earlier in the week Mahmoud Vaezi, the telecoms minister, said the ministry was studying the possible launch of Telegram calls in the country.

Telegram voice calling service was launched on March 30 in Europe.

According to the company�s official statement the service is currently available in Europe, South and North America, Africa and several Asian countries including Iran and Uzbekistan.

OTT Service

Technically the service is considered an Over-the-Top (OTT) voice calling service. OTT service providers deliver audio, video and other media over the internet and bypass the traditional operators� network.

Since OTT players do not require any business or technology affiliations with network operators for providing such services, they are often known by the term �Over-The-Top� (OTT) applications.

OTT providers do not contribute directly to the telecom revenues; however, their services can only be used by users who have an Internet subscription, which contributes to operators� revenues.

On Wednesday Vaezi said, �Telegram officials and the government are in talks about the planned launch of the service in Iran. The primary concern is its inevitable impact on the business of Iranian mobile network operators.�

Iranian mobile operators were apparently reluctant about the launch of the Telegram call service and the negative impact it can and will have on their earnings.

Whatsapp, another messaging app owned by Facebook, has offered both voice and video calling for over a year.

Meanwhile, Skype, which also offers a mobile version can do the same.