How are text messages transmitted through iMessage?

[air23cary]

I have a fully loaded late 2012 mini, and two thunderbolts attached to it. I noticed tonight when using iMessage that the wifi on my iPhone was off but sending texts via my Mac still worked. I couldn't understand how that was possible. Later I realized bluetooth was still on, so it must transmit through that. So I turned off bluetooth, and sent more texts on my Mac. With no wifi and no bluetooth, my cpu was still sending out legit texts. Only when I shut down my iPhone could I fail to get a message out. So I know the iPhone at least has to be on. My question is how does it send/receive transmissions if it's not wifi or bluetooth?

This contrasts with phone calls, which I receive on my Mac and iPad when wifi is on.

 

[Intell]

They go out to Apple's servers as an internal iMessage of sorts, get sent to your iPhone, and get resent as an SMS.

 

[simonsi]

If your iPhone is on it likely has a cellular data connection, iMessage will use that.

Disable cellular data in the iPhone preferences, I'll bet all iMessage (inc via your desktop/laptop), will be offline and you will only have SMS from the phone available.

 

[tdale]

But if wifi and BT are off on the Mac, how does the Mac send the message to the iPhone? The Mac is merely an extension of the iPhone, so how can the Mac send anything anywhere with no wifi and no BT?

 

[simonsi]

But if wifi and BT are off on the Mac, how does the Mac send the message to the iPhone? The Mac is merely an extension of the iPhone, so how can the Mac send anything anywhere with no wifi and no BT?

To my knowledge your Mac needs an internet connection to send iMessage or Handoff SMS via your iPhone, it can't send via BT to iMessage. That would be wired ethernet, WiFi or tethered to a mobile with cellular data.

I thought your were referring to turning off BT and WiFi on the iPhone.

 

[tdale]

To my knowledge your Mac needs an internet connection to send iMessage or Handoff SMS via your iPhone, it can't send via BT to iMessage. That would be wired ethernet, WiFi or tethered to a mobile with cellular data.

I thought your were referring to turning off BT and WiFi on the iPhone.

I just checked the requirements as I get mixed up between Continuity and Handoff. Handoff uses same wifi network and BT, Continuity (calls,SMS that this thread is about ) requires the same wifi network

The iPhone makes and receives calls and SMS, the Mac is just an extension of the phone. If the Mac is supported, and on same wifi network, it will ring. If wifi is off it wont work as there is no means for the Mac and iPhone to be connected.

iMessages go from any device to Apple servers via internet (cellular or wifi) and to the recipient