As with all the other mobile IM platforms authentication is required (and therefore a phone number), however there are ways around using a mobile number. The easiest is using a landline and voice authentication. Telegram will first attempt to send a text message, and if that fails after two minutes call with an automated message that contains an authentication code.
You would still need a mobile platform though, which brings us back to that contact list. The simplest option is to use a factory erased old phone that still supports Telegram (at least Android 4.1 or iOS 9.0 at the time of writing). Then you follow the regular install route and authenticate the web client. As with the second option you can use a dummy google account that has an empty contact list. You can then either use Telegram on that phone, or use it to authenticate a web client on your PC.
If you don't have one of these, there fortunately are emulators that allow you to run these from a PC. Assuming you don't connect that same emulator instance to an account that has a contact list, Telegram will never have the opportunity to access it. If you opt for this route, then:
- Install emulator on PC (for example this one)
- Log into google (you will need an account to access the play store - but this can be a dummy account without a contact list)
- Install Telegram from the Play store
- Open Telegram
- Select your country
- Enter your landline phone number
- Click next (and wait for 2 minutes for the text message to fail and Telegram to call you with an automated message)
- Enter the verification code into Telegram
- Now authenticate the web client (on your PC's browser, so outside of the emulator)
That's it. I would opt for the factory reset old phone route though.