In a system for providing user input information to multiple independent, concurrent applications, the applications send subscription messages to a device receiving user input such as a telephone receiving key presses from a keypad. Each subscription message identifies a pattern of user input that the application is to be notified of. The device monitors the user input to identify the occurrence of the identified patterns. When a specified pattern of user input is detected, the device notifies the corresponding application via a signaling channel linking the application with the device. The subscription messages use regular expressions including various formats to specify the patterns of interest, such as a single digit (explicitly or wildcard), one of a set of digits, a range of digits, and a repeating pattern of digits. The subscription messages can also contain tags associated with the regular expressions, which are returned to the application upon reporting the occurrence of a pattern to enable the application to readily identify the context of the notification.