Originally Posted By: Ren

Once have the hikers phone number and a message to send, it can be automated, until get a response.
Spammers/scammers can't hide their phone number.

Thats what they said about caller ID when it first came out. Nothing is 100% secure, its only a matter of time before whatever system is used becomes hacked/abused.

But still doesn't fix the original issue of the hiker not answering, so he sees a number coming in on a 'secure' service and doesn't recognize it, would he have answered it?