An MMSC generates an encoded token based on a message-locator (or part-locator) and the recipient's subscription identification. The token is inserted in the message-locator (or part-locator) field of a notification sent to the recipient. When a MMS message request is received, the MMS decodes the message-locator (or part-locator) field to authenticate the subscriber and the locator. This authentication effectively allows access from a substitute URL location included in the notification to a real URL location for the content.
