Since the introduction of Mobile number portability in 2002, the prefix (here 0170) is no longer a indicator for the mobile radio network.
Originally, the phone code 0170 was assigned to Telekom. Currently, however, this can be used or be active in a different german network.
Which provider is that?
The same applies to the provider. Originally to Telekom assigned can this number theoretically be in use at every other german mobile provider.
Call a german 0170 mobile number from abroad
To call a mobile number with the prefix 0170 from abroad, you must dial the area code for Germany (+49 and 0049) at the front. In addition, you have to remove the 0 from mobile phone code. The final phone number then has the following form: +49170...