According to one aspect of the present invention, a wireless telephony device is equipped with an optical image sensor, and a lens for imaging an object onto the sensor. The optical sensor permits a variety of useful functionality, including decoding of bar codes, watermarks, etc., from objects imaged by the sensor. One application of such a device is to interact with a remote computer system using data decoded from a bar code or watermark. For example, the device can be used to scan image data from an item depicted in a catalog, and then to transmit an order for the item from the catalog's on-line web store--using digital data decoded from the image to identify the desired item.