Apple Wireless Messaging Service
A defunct subscription-based electronic messaging service that allowed a Newton device equipped with a Newton Messaging Card to send and receive text messages, as well as send and receive voice messages via telephone. A seven-digit personal identification number or PIN was used to identify a user on the service. A separate four digit PassCode was used to securely access text messages, voicemail messages, and change various account settings.
Internet Archive: Apple Wireless Messaging Service: How To Use
Apple Support: Apple Wireless Messaging Service: No Area Code In PIN
Apple Support: Newton Messaging Card: How to Setup