A transit system for use in combination with a mobile device for providing access for a user of a mobile device, the transit system comprising: a transit fare collection terminal; a transit agency computer system operated by a transit agency for communicating with the collection terminal via an element of a wireless cellular network, the transit agency computer system comprising a processor configured to execute a process to generate access control data specific to said transit agency, whereby the access control data is provided to the element of the wireless communications network and is transferred over the wireless network to the mobile device; and a communication module coupled to the collection terminal, the communication module configured to mutually authenticate with the mobile device using a contactless short range communications technology, the mobile device comprising a wireless data transfer element capable of communication and data exchange over the wireless network and a contactless element capable of communication and data exchange using the contactless short range communications technology, the wireless data transfer element and the contactless element being embedded within the mobile device, the contactless element further having at least a part of a dynamic memory storage element configurable using the wireless network, wherein the mobile device is configured to receive the access control data from the element of the system via the wireless network, wherein the access control data comprises an encryption key and fare computation data specific to the transit agency, and wherein the access control data is stored by the contactless element and authenticates that the user is entitled to access the transit system, wherein the mobile device is further configured to use the encryption key to mutually authenticate with the collection terminal using the contactless short range communications technology, wherein the transit agency computer system comprises means for determining the location of the mobile device and is configured to generate and automatically transfer the access control data to the mobile device in response to determining that the location of the mobile device is in geographic proximity to said transit system. a transit fare collection terminal; a transit agency computer system operated by a transit agency for communicating with the collection terminal via an element of a wireless cellular network, the transit agency computer system comprising a processor configured to execute a process to generate access control data specific to said transit agency, whereby the access control data is provided to the element of the wireless communications network and is transferred over the wireless network to the mobile device; and a communication module coupled to the collection terminal, the communication module configured to mutually authenticate with the mobile device using a contactless short range communications technology, the mobile device comprising a wireless data transfer element capable of communication and data exchange over the wireless network and a contactless element capable of communication and data exchange using the contactless short range communications technology, the wireless data transfer element and the contactless element being embedded within the mobile device, the contactless element further having at least a part of a dynamic memory storage element configurable using the wireless network, wherein the mobile device is configured to receive the access control data from the element of the system via the wireless network, wherein the access control data comprises an encryption key and fare computation data specific to the transit agency, and wherein the access control data is stored by the contactless element and authenticates that the user is entitled to access the transit system, wherein the mobile device is further configured to use the encryption key to mutually authenticate with the collection terminal using the contactless short range communications technology, wherein the mobile device is configured to receive the access control data from the element of the system via the wireless network, wherein the access control data comprises an encryption key and fare computation data specific to the transit agency, and wherein the access control data is stored by the contactless element and authenticates that the user is entitled to access the transit system, wherein the mobile device is further configured to use the encryption key to mutually authenticate with the collection terminal using the contactless short range communications technology, wherein the transit agency computer system comprises means for determining the location of the mobile device and is configured to generate and automatically transfer the access control data to the mobile device in response to determining that the location of the mobile device is in geographic proximity to said transit system.