assure the data rates required to receive next-generation services. Access networks around the world evolved to include more and more optical fiber technology. Optical fiber already makes up the majority of core networks and will start to creep closer and closer to the customer, until a full transition is achieved, delivering value-added services over fiber to the home (FTTH). Access process The process of communicating with a network begins with an access attempt, in which one or more users interact with a communications system to enable initiation of user information transfer. An access attempt itself begins with issuance of an access request by an access originator. An access attempt ends either in successful access or in access failure - an unsuccessful access that results in termination of the attempt in any manner other than initiation of user information transfer between the intended source and destination (sink) within the specified maximum access time. Access time is the time delay or latency between a requested access attempt and successful access being completed. In a telecommunications system, access time values are measured only on access attempts that result in successful access. Access failure can be the result of access outage, user blocking, incorrect access, or access denial. Access denial (system blocking) can include: Access failure caused by the issuing of a system blocking signal by a communications system that does not have a camp-on busy signal feature. Access failure caused by exceeding the maximum access time and nominal system access time fraction during an access attempt. Charging for access An access charge is a charge made by a local exchange carrier for use of its local exchange facilities for a purpose such as the origination or termination of network traffic that is carried to or from a distant exchange by an interexchange carrier. Although some access charges are billed directly to interexchange carriers, a significant percentage of all access charges are paid by the local end users. Mobile access networks GERAN UTRAN E-UTRAN CDMA2000 GSM UMTS 1xEVDO voLTE Wi-Fi in* WiMAX Optical distribution network A passive optical distribution network (PON) uses single-mode optical fiber in the outside plant, optical splitters and optical distribution frames, duplexed so that both upstream and downstream signals share the same fiber on separate wavelengths. Faster PON standards generally support a higher split ratio of users per PON, but may also use reach extenders/amplifiers where extra coverage is needed.