Until 2005, some localities still a seven-digit local number ( nnn-nnnn ). Until the 1990s, there were also certain regions with three-digit area codes and five- ( n-nnnn ) or six-digit ( nn-nnnn ) phone numbers. Even shorter numbers to exist in previous decades, especially in small towns and before direct distance dialing became universal.Numbers starting with 400n are reserved for a special case of non-geographic numbers (see below). Numbers starting with 1700 are within the service area of the Oi Fixo landline operator for some Internet Service Providers (ISPs) to provide dial-up Internet access to certain Oi customers. Such customers have special pricing agreements with Oi and are charged less than the price of regular local calls when calling such dial-up access numbers. Local directory assistance can be obtained by dialing 102 , but the service is charged as a regular local call in most instances except from payphones. However, all local landline telephone companies offer on-line directory inquiries on their s. Mobile lines are not available for inquiry, for privacy and security reasons.