Q: Text message forwarding - no code on iPad or Mac

Had the same problem after having changed my Apple ID this morning; code not showing up on any of my devices after having had to log back in again to iCloud on iPhone, iPad and iMac - for both Cloud features and Messaging and FaceTime.

Problem solved by ensuring that Keychain is activated across all devices. It would appear that you have to have Keychain activated across your devices before it will work.

I just fixed this issue.  Spent many hours on my own and with Apple Helpdesk.  Make sure under Settings/Messages/Blocked - your own phone number is not blocked.   This causes an issue of Mac not showing the code when you turn on the Text Message Forwarding.  Once its un-blocked, you should see the pairing code.  Thanks.

I can confirm the way I fixed this problem was to :

1. Disable iMessage and Enable on my iPhone 6 Plus

2. MBP iMessage Pref. and made sure my phonenumber was enable

3. Close my iMessage on my MBP and open it again

4. iPhone 6 plus start forward again and a windows came in iMessage (MBP) with big numbers.

If someone still have the same problem, go to this webpage:

http://www.igeeksblog.com/sms-relay-not-working/

It solved my problem!

I struggled with this for while until realising that I had recently updated to a new iphone and was still logged into iCloud and using iMessage on my old iphone. Once I logged out of iCloud and turned off iMessage on my old phone, I turned on Text Message Forwarding on my new iphone the code appeared on my mac book pro. All working fine now

The ONLY thing that worked for me was this:

1.  I added a SECOND email address to both my Mac AND iPhone

2. I unchecked the first email address on both devices.

3.  Signed out and in of iMessages on both devices.

4.  Went to Send & Receive on iPhone and checked only the new email address and my phone for "Start New Conversations"

5.  Did the same on the Preferences/Accounts on my Mac.

6.  Went to iphone:  Settings/Messages/Text Message Forwarding and turned on the button for the Mac.

7.  Code FINALLY appeared on the Mac.

It worked!  thanks

Yes the fix helped here as well. Apple REALLY needs to get it together for Apple ID's. Had a 2 day nightmare trying to figure this out!

I did everything harshc4 suggested, did a bunch of re-booting, turning things off and then on again, etc. and also made sure all my devices had the same list of "You can be reached by iMessage at". Still no joy. But it turned out one more thing was also necessary. I had to make sure that my phone was set to "Start New Conversations From" my phone number. Both Mac and iPad had that set right, but for some reason, my phone was set to start conversations from @icloud.com. Once I fixed that, presto, the six-digit codes showed up. Hope that maybe helps somebody.

sign out and sign in from my Apple ID on my MBP did the trick.

Thanks for the help, Dave! I was at a loss for a few minutes...

This is what I did:

Settings >> Messages >> Turn off iMessage >> Turn on iMessage >> Text Message Forwarding >> Slide "Text Message Forwarding" on = CODE APPEARED.

None of the suggested (iMessage off/on, email address spec, network reset - rebooting - I did all of that) worked. Now one thing - amazing as it may be - worked although I must admit it could be coincidental with other phenomena since some things seem to appear and disappear over time. For instance the Text Message forwarding appears only many minutes after iMessage is enabled again.  I own 3 iphones and ipads. One of my Phones would easily connect with one iPad (each person owns a set). The next one wouldn't. Until I realized it had the name 'iPad'. I thought: "maybe a bit confusing let's change it to 'iPad van Katja'" . Bang. Message box came up on the Pad, Phone and Pad linked, fixed.

After following almost all the above directions and implementing a few, this is what finnally got mine to work... Thanks Charles!

Thanks for your helpful post.  I've been searching for ages and this worked fine for me. 

The only thing I need to work out now is how it got un-ticked in the first place, it was all working fine yesterday

I too found that the solution works (the solution posted in the first message in this thread), but it reminds of the ouroboros, the mythical snake that's always chasing its own tail.

The problem is that I employ this solution about once a month, when my peaceful iCloud/iMessages interconnectivity all come crumbling down. I don't know what causes it, so it's frustrating when trying to troubleshoot. I go through and revoke all my application-specific passwords, assign new ones, turn everything back on, enter the Text Message Forwarding codes on my various Macs (three) and iPads (four), rinse and repeat. I will be back on here in another month for reasons that I can't explain, but I roll with the punches.

It just works...once a month.