receiver property provides the phone number of the message's receiver.
var receiver = instanceOfMozSmsMessage.receiver;
This is a non-standard implementation, but it is discussed at W3C as part of the System Application Working Group.
|Messaging API||Editor's Draft||Editor Draft (WIP).|
For obvious reasons, support is primarily expected on mobile browsers.
|Feature||Chrome||Firefox (Gecko)||Internet Explorer||Opera||Safari|
|Basic support||No support||No support||No support||No support||No support|
|Feature||Android||Firefox Mobile (Gecko)||IE Mobile||Opera Mobile||Safari Mobile|
|Basic support||No support||12.0 (12.0) Moz||No support||No support||No support|