How does Messages work with SMS?

Just to be sure, do all of your questions refer to these features on your Mac? They were added to the Mac with the upgrade to OS X Yosemite. You'll need to upgrade to that from Mavericks to use them.

As for the Dock icon, new messages have a small blue dot to the left of the contacts name - it looks just like a new message on the iPhone.

1) does it show only special Apple messages, or do regular SMS messages come here also? Can I send text messages to phones that may not be iPhones? I just got an SMS on my iPhone that didn't show up on the Messages application I have open on my MacBook Air.

Apple Messages on a Mac talks to other Apple Messages clients via Apple's Messages server.

The Mac Messages app and Apple's Messages server does NOT do SMS.

It is possible to configure the Mac Messages app to talk to other Messaging servers, such as AOL Instant Messager (AIM), Google Talk, Yahoo, Jabber, etc... Users that use these other instant messaging services can see your messages on whatever devices support those services.

But ONLY Apple devices support the end-to-end encrypted Apple Messages protocol.

In Yosemite 10.10 or newer OS X version, IF AND ONLY IF, you have an iPhone running iOS 8 or newer, you can setup up Continuity which will, if your iPhone is on the same local network as your Mac, will allow the Mac's Messages to send SMS via the iPhone and whatever carrier your iPhone is using for SMS.

<Use Continuity to connect your iPhone, iPad, iPod touch, and Mac - Apple Support>

2) The Dock icon for my open Messages application has a little red "1" on it, but I don't see a new message in Messages - how do I tell which are new, unread messages?

The badge is suppose to indicate there is something for you to read.

3) once I'm signed in to Messages, can I make and take calls on my OS X 10.9.5 laptop through my iPhone on the same wifi network?

No. You need Yosemite 10.10 or newer to use Continuity.

<Use Continuity to connect your iPhone, iPad, iPod touch, and Mac - Apple Support>

NOTE: Continuity also works with other iOS devices (iPads, iPod Touches) which are running iOS 8 or newer (my Wife does this using an iPod Touch when her iPhone is in her purse in another part of the house).

1) In Mavericks, you are using iMessage, not SMS. That's why you are only connecting with iPhone users.

2) I've not seen a window that shows just the new Messages. Much like the phone, new Messages move to the top of the list. If you don't open it, however, it will gradually get pushed farther down the list by incoming messages. I've had to scroll pretty far down sometimes to find the message giving the indicator.

ℹ More Info.

More than ten years ago Apple included the iChat app fro the first time with the OS.

It was then just a text chatting app and Apple arranged with AIM/AOL that Apple IDs issued by Apple (@mac.com back then) could be used as valid AIM Screen Names.

Back then the app was exclusively AIM based or the Bonjour (then called Rendezvous) for LAN based Mac to Mac chats.

iChat 2 added Video and Audio Only chats.

iChat 3 added Jabber and GoogleTalk could be made to work with the app.

iChat 4 added the Google option to Add an account due to Google's strange Server name issue.

iChat 6 adds Yahoo (badly) as it only does text chats and no other features.

Mountain Lion (OS X 10.8) brings iMessages added to the Folder and a reworking of the Chat window (forcing tabbed chats effectively) and the new name of Messages. The App numbering continues with it being called version 7

The iMessages account tends to ask for an Apple ID as you open the app for the first time. (it will bring older accounts across from System Preferences > Internet Accounts if they exist).

The iMessages account in the Mac version and the Messages app (and it sending of iMessages) on the iPhone can be linked by adding the Apple ID to the iPhone after it's number has verified (Registered in fact).

Both Mavericks (OS X 10.9) and Yosemite (OS X 10.10) both list Messages as being version 8 thought the updates to the OS (which is not the version counting process used before this time.

The Yosemite version can do SMS, or Text Forwarding as it appears in the Settings of the iPhone Version, which, as has been said, has to be at iOS version 8 at least.

So.

Messages can do IM Chats over the AIM service, the Jabber service, the Yahoo service and the Bonjour connections to other Macs on your LAN as well as the iMessages service run by Apple. (This may require you to have different IDS for each service)

Re Question 2.

As BobHarris says it is supposed to tell you if you have Unread items.

Try Right Clicking the Dock icon and seeing if it lists the Chat it thinks you have not read.

If it does can the app bring it back to the Chat window if you select it ? (it may not list or it may not show the chat if it was fully deleted rather then dismissed)

If it does not go to Applications/Utilities and open the Activity Monitor app.

Find the Dock in the List and highlight it (it will be close to the Finder but not have an icon)

Once highlighted use the Quit icon top left (grey icon with what looks like a Stop Sign hexagonal on it.).

Confirm Force Quit.

The Dock will disappear from view on the Desktop and then reappear as the Listing appears in Activity Monitor as it starts up automatically again.

The Numbering on the Dock icon for Messages should be sorted now.

Re Question 3):-

I tend to be very pedantic about what is Messages (the app) and what is iMessages (the Account).

I can see that you mean that when iMessages is logged in but you have said the App in the way you phrased it and then could mean one of or many services in fact and will depend in some cases as to whether the iPhone is logged into them as well.

You might want to read this first Link your iPhone number and Apple ID to use iMessage and FaceTime - Apple Support

Enabling Messages on your iPhone will cause it to Register the Number at the iMessages server and it will read "Verifying" until this completes.

The Mac versions expects an Apple ID that is linked to a valid iCloud account (It does not have to be the same as your iCloud account).

Once this has Verified and logged in your can send to the iPhone Number from the Mac ID and vice versa.

Adding the Apple ID to the iPhone in Settings > Messages > Send and Receive then the Apple ID and iPhone Number become linked.

Pop ups will appear on the Mac version which your have to Accept to add the iPhone Number to the Mac's settings.

On both version there are then settings for which of those are to be used when Sending new Messages.

iMessages sent to either your iPhone Number or Apple ID will appear on both devices and can be replied from there.
The replies will show up (on the Contacts end) as coming from the ID it was Addressed to (independent of the "Start From" ID) - if someone sent to the iPhone Number and you sent back from your Mac it would still address your contact as coming from your iPhone Number even if the Mac version is set to "Start From" the Apple ID.

Of course you could also be logged into AIM/AOL with a Screen Name and/or a Jabber ID such as Google Talk and/or a Yahoo account and have either apps or a web page login on your iPhone

9:46 pm Sunday; January 3, 2016

Hi,

Messages app using the iMessages account does not "Download" iMessages.

The iMessages servers continually push iMessages to the devices that are Registered with iMessages.

If they are Off line then the Servers will continue to try to send them to your devices. There do appear to be Time Out limits to this though. I have had iMessages 7 days on my Mac after I had been away for that time. I have seen one post here saying it worked for the Poster at 9 days and another one at 11 days.

In a set up that might have one Mac, one iPhone and an iPad the Number for the iPhone gets registered when you enable the App.

At that point the iPhone can only send from it's number (and of course receive ones sent to the iPhone Number)

The Apple ID on the Mac version is what enables that version to iMessages from the Apple ID (it can of course Receive At this ID as well)

If you now Add the Apple ID to the iPhone settings and accept the resulting Pop up on the Mac then both can then send and Receive on both the Number and the Apple ID.

(this does depend on both the Number and the Apple ID being selected to Send and Receive on both devices).

Adding the Apple ID to the iPad will trigger the pop up to say what the iPhone is using which then adds the Number to the iPad list of Send an Receive options.

Additional info.

The iPhone can also be set to use SMS (green ballooned sends iMessages ones are blue).

These SMS items will not show up on the Mac (if it does not have Yosemite or Above)

A Contact's iPhone may not be sending you iMessages (all incoming ones are grey which is not helpful):-

1) They may be on a carrier service at that time that does not support iMessages or without a WiFi connection as a replacement.

2) They may not have registered for iMessages.

How do you know they have been sent from an iPhone ?

Once someone has linked and Apple ID and iPhone number their Mac can send as if it were the iPhone - if you send to the Number from either device they will reply no matter what device they use as if it were the iPhone by sending from the iPhone Number at their end.

An iPhone will default to sending via SMS if it does not have an adequate way of sending iMessages (if it is set up to use SMS).

iMessages are deleted from the server once accepted by the device it was sent to.

They are sent to each device uniquely based on a login that also uses the device's Serial Number.

If you delete an iMessages on one device it is deleted on that device only - but there is no going back as there is nothing on the server to send to you.

A Mac added to the set up will only get new iMessages from that period onwards.

So a second Mac that you add to the set up and then Login will not get any older iMessages that have been sent to you on other devices.

On the whole

I think your set up might be working as it should in the ways I have explained.

That's not to say it is what you expected.

iMessages are not like emails that an App "fetches" from the servers. They are pushed at your devices until accepted then deleted from the server.

This means your iPhone's "copy" may be accepted by the iPhone before the Mac is even On.

Once the Mac is On it will accept the iMessages "Copy" for the Mac and then that gets deleted.

At this point it only exists on your devices.

I am presuming this:-

... and I logged on to it from another machine and the messages list is completely empty

Is referring to a new Mac added to the list of devices using the same Apple ID.

It should also have triggered the pop ups which need to be accepted to have the iPhone Number added to the List or Receive At (and the Send from drop down).

However as I have said it will not get old iMessages - they don't exist.

You now seem to be talking about multiple devices, all of which may not be working the way you expect them to. It is difficult to judge whether they are works as they should although I suspect they are.

However the doubt I have is making it difficult to be coherent in all possible circumstances.

8:18 pm Wednesday; January 6, 2016