Registration issues

First of all, you need to make sure you are entering your cell phone number in the international format:

+(country code)(city or carrier code)(your number)

Let's say you live in the USA and your cell phone number is 555-123-4567, then you need to enter +15551234567.

As of February 2017, Telegram supports VoIP numbers again, so you can now register with virtual numbers such as numbers issued by Google Voice. If you have a real SIM card phone number and it's not a virtual number (VoIP), contact and provide the following details to them:

  1. Which company did you get your SIM card from?
  2. What country are you in right now?
  3. Are you able to receive SMS? Try sending and receiving messages from friends. If not, you are not able to log in to Telegram.

Country specific SMS delivery issues

Brazil: Oi, formerly known as Telemar, is the largest telecommunications company in Brazil and South America.

They offer their customers a website where they can configure their account, e.g. blocking SMS from short numbers. It's important to disable the setting, in case you do not get any verification/login SMS. Login to and disable "Recepção de Sons Imagens e Bate papo".