Abstract: A scalable call processing node includes link interface modules capable of processing n calls per second and call server modules capable of processing m calls per second, n is variable relative to m by changing the relative numbers of call server and link interface modules. In addition, call server modules can perform subsecond switchover when a call server fails without requiring inter-call server transfer of call state information.

Abstract: Methods and systems for performing sales transactions using a mobile communications device and without requiring text messaging or paging services are disclosed. In one example, a subscriber desiring to purchase goods or services proceeds to a point of sale device where the purchase price for the goods or services is totaled. The subscriber then initiates a voice call with a central transaction server. The subscriber provides a point of sale device identifier and the purchase price to the central transaction server. The central transaction server contacts a local transaction server using the identifier provided by the subscriber. The central transaction server also prompts the subscriber to select the payment account for the transaction and verifies that the subscriber has sufficient credit to purchase the goods or services. The central transaction server locates a pending transaction entry in a database local to the point of sale using the device identifier provided by the subscriber.