There are no standard lengths for either area codes or subscribers' numbers in Austria, meaning that some subscribers' numbers may be as short as three digits. Larger towns have shorter area codes permitting longer subscriber numbers in that area. Some examples:
1 Telering was bought by T-Mobile in 2005. As of 2006, Telering uses the network-infrastructure of T-Mobile. As a special requirement of the European commission, many of the former transmitters and frequencies previously operated by Telering were given to Orange and Drei.
2 BoB is a discount service of A1. yesss! was a discount service of Orange, now sold to A1. Eety is a discount service of Orange (now 3). Schwarzfunk was a discount service of T-Mobile.
Due to number portability, the code is not a safe way to evaluate the provider of a phone number. The providers assign only in exceptional cases (special sort of custom numbers, more expensive) non-existing numbers with a different prefix, and this is handled similar as porting an existing number from the desired network. However, the providers still have the administrative sovereignty over their own prefix.