iMessage on my mac says every contact is not registered with iMessage

I just installed Yosemite, and have been trying out iMessage for more or less the first time. Immediately when I tried to send a message to a phone number of a contact it was made red, and I got an error message.

I never really tried doing this when I had Mavericks, so I can't say whether it was caused by the upgrade or what.

Anyone still having this issue?

Note: I am not sending messages to other Apple devives, but I was told (by none other than David Pogue's Yosemite review) that the current version of iMessage can send messages to any old phone number. True?

Thanks.

Yes and no. From what I understand you will be able to send an sms to a non-iphone with Yosemite, but only if your iPhone is near you (ie on the same wifi network). But that will only work with iOS 8.1 installed on your phone. Currently my Mac can see the non-iPhone caller, but I can't text him.

Tomorrow when 8.1 is released we can try it and see if it works. ;-)

I'm so confused. I don't even have an iPhone. I rock an Android for a phone. Sacrilege!

Anyway, I was just hoping to be able to use my iMac's iMessage to ocasionally send/receive texts. That's what Pogue suggested Yosemite could do. So far I am not impressed. I seriously need to have an iPhone and keep it "near?" I can't even comprehend the words I'm reading -- if they are correct!

I too am still having the issue of all contacts on my macbook saying "not registered with iMessage." It is a real bummer, been like this since Early September. I upgraded to Yosemite, but went back down to Mavericks because I couldn't run a lot of my programs, but even while on Yosemite iMessage still did not work. When I downgraded to Mavericks I had to erase my hard drive completely and reinstall OS X from the original disc, I thought after doing that the iMessage might work, but it still didn't and doesn't. Why can't Apple fix this if so many people are having the same problem?

Myself as well, I'm hoping it works, but I think I can throw Apple a bone here with something I've observed:

Semi-recently (within the last 2-3 months) my 5s was acting up, it lost the capability to talk to cell networks. The Apple Store switched it out with a brand new one.

1 week later, my iPhone 6 arrived and I took the offer from Apple to swap out my 5s for a gift card that paid for the cost of the iPhone 6.

The Kicker: When I log into iCloud, I see my previous two iPhone 5s phones, my iPhone 6, and my MacBook Pro. However, when I log into Find my iPhone, I only have my iPhone 6 and MacBook Pro listed. I am unable to remove the previous two iPhone 5s' from my iCloud account.

I believe these two phones sitting in here are causing a conflict. Would you (and anyone else as well) check this to see if its a consistent issue?

Thanks Ralph. I think it was the plist that finally made it work. In Yosemite there is a prompt that asks you if you want to use your Mac to receive and respond to text messages, followed by a minor passcode exchange, then everything works.

My experiences - mine stopped working at some point in Mavericks. I hoped the upgrade to Yosemite would fix it but no luck

Been dealing with an Apple support guy all week, nothing fixed it. Tried using an new test account on my own mac, nada.

At his suggestion, with my girlfriend logged into her own mac I signed her out of imessages and signed in myself - it worked fine. So it would appear something definitely specific to my Mac.

In desperation I did a wipe and clean Yosemite install on my mac yesterday. Still didn't work :-(

Will report back to the Apple guy tomorrow.

After spending a half hour working on this bug I finally got it to work by going to the iCloud Preferences on my Mac, fully disabling it, and then re-enabling it from there. Nothing else seemed to work, but I can confirm as soon as I did that I could send SMS again from Messages

I have the same issue almost. My friend and I have apple devices (he has an iPhone, me an iPod and a Mac, I mainly use the Mac) but both devices tell me he isn't registered with iMessage, and his does the same. I have tried resetting my network settings, as has he, neither of us have the other blocked, and we have the right number/email. Any suggestions?

Just thought I would chime in on this. I was having this issue on my iPad (3rd generation with LTE) on 8.0.1 and my 2010 MacBook Pro with Yosemite : I couldn't send or receive messages to/from anybody that I know had iPhones and were using iMessage (wife, family, friends, etc.). But, I could ALWAYS send and receive messages to/from them using my iPhone without issue (across all versions of iOS 7 and 8).

My set up is that I have my phone number as the ID from which to start conversations and in addition I have my same Apple ID linked to all three devices. I've tried all the suggestions of logging out of iCloud, logging back in, etc. (with FaceTime, iMessage, etc) but nothing has seemed to help. This has been the case across multiple updates as well.

But now, all of a sudden, it seems my situation has improved slightly as I seem to now have contact specific issues on the iPad or Mac. For example on my iPad, I can send/receive messages to/from my wife but when I try to send a message to other friends, they're still showing as red when trying to start a new conversation, a "Not Sent" or whatever error when I try sending a message as part of an existing conversation or it tries to send as a text message (green "SEND" text). The other weird thing is, for these contacts the conversation gets updated with (blue iMessage) messages that are sent/received from the iPhone (and it's not continuity as I've isolated the devices on separate networks or they're on cellular with bluetooth off). As if the record of the conversation on the iCloud can be seen by these devices and updated but the ability to send is blocked. This is frustrating. But at least I can process messages from the person I exchange them with the most so that's a small relief.

After checking another thread, I found this, which worked for me -

On my iPhone I went to settings/Messages/Text Message Forwarding. I turned off the slider for my MacBook & then turned it back on. A code showed up on my MacBook, which I then entered on my iPhone. All is working fine now.

I'm not sure if anyone is still having this issue but it happened to me this morning without warning. I hadn't made any changes but suddenly Messages on my Mac stopped working, while complaining that all of my contacts are not registered with iMessage. By a stroke of luck, I was able to solve the problem for myself. I needed to access iMessage and the only other Apple device I had kicking around was a company iPad (on which I had never previously signed in). I signed into iMessage on that device and Messages on my mac started working immediately. Maybe if anyone is still having trouble, try signing in your iMessage account on a friend's device?