SMS spoofing and attacks are technically possible (although they are very minimal in practice today) and posting to google+ by sms is going to be of no exception.

In order to protect and secure your sms posting, google+ supports security PIN number to be included part of your post which provides that extra layer of security.

A google+ SMS pin must be

• 4 to 8 alpha numeric characters
• allowed characters are A-Z and 0-9
• pin’s are case sensitive

How to setup a secure PIN to prevent from SMS spoofing in Google+?

How to setup a sms pin?

Just head to google+ settings and look under notification delivery section a setting called Add SMS security PIN (refer image above)

How to use the pin?

The pin must be first thing in the google+ sms post right before the post content and the circle or individual email addresses

SMS post example with a security pin

ABCD1234 This is a sample google+ sms test post +circlename

here ABCD1234 is the secure pin setup using google+ settings (refer image above)

Add a SMS pin to your google+ account and enjoy that peace of mind while posting by sms.