What does “when iMessage is unavailable” mean?

Question

In the settings for the iOS 5 Messages app there is an option to send messages as SMS "when iMessage is unavailable". Under what conditions is this the case? Is it merely the obvious (no data connection available or the iMessage server is down, or the message sits undelivered for a time), or is it more subtle (for example, the service simply not having had time to confirm that the recipient has iMessage enabled, or that the recipient's device cannot be contacted at the time of sending)?

Phrased another way: what are the conditions under which an (intended) iMessage wold go undelivered, and are there other events that would cause a message to be delivered as an SMS?

Answer 1

It means either

• when the device is unable to determine if a message has been delivered over the iMessage transport successfully. When a successful delivery occurs you see a little 'Delivered' notification below the message in the history, and after a period you should have the option to resend as an SMS

• or the recipient has no registration with the iMessage server to indicate that it could use the iMessage transport and will use SMS instead.

Answer 2

Another scenario I've discovered is when I'm connected to a WiFi signal that requires HTTP authentication. If I bring up the browser and authenticate, I'm fine. However, if I just let the iPhone connect to the WiFi, but I don't bring up the browser to authenticate, then the data network will be seen as dead, and any iMessage attempts will fallback to SMS (green dialog boxes). But then, as soon as I bring up the browser to authenticate, my conversation will switch back to iMessage (blue dialog boxes). So unless I remember to keep re-authenticating to the wireless network with the browser, my best bet it to just "Forget this network" and allow the iMessage to be sent over the AT&T data network, then it will remain as an iMessage.

Answer 3

An example of a failed iMessage: I do not have a data plan. If I send or am sent an iMessage, and I happen to walk outside of the Wi-Fi point I'm connected to, it can fail to send, forcing me to then send as SMS.

Hope this helps.

Answer 4

iMessage uses an internet connection to send a message to another Apple device, if you do not have a 3G data plan or internet connection it will not work, that also goes for the person who is receiving the message, if they do not have a connection it will fail to deliver.

I know someone with a 3G without a 3G data plan (dont ask) and in order to send a SMS you will need to double tap the sent message and choose 'send as SMS'

Answer 5

Okay peeps, listen up! iMessage is an IOS 5+ ONLY software that sends sms texts between 2 or more IDevices that BOTH have IOS 5+. It uses your cellphones internet connection to do this. If iMessage is enabled, and you send a message to another user that has IOS 5 or IOS 5.1, the message will show up on your screen colored blue instead of the usual green color of texts (Note: This is a good way to check if iMessage is working, as well as a way to check if the person you are texting has IOS 5)

Now for the perks of iMessage. When using iMessage, all texts sent using this feature are completely free through a deal Apple made with AT&T, Verizon and Sprint (Altough Sprint is like a secondary company, so if you are using google voice, and have a different number on Google Voice then your actual cell number, iMessage MIGHT be disabled) so if you bought an IPhone, and are using a SIM card from a different company, well, tough luck I guess. There IS a reason why only SOME companies sell Iphones you know.

When using iMessage, if you leave the screen on the messages app, waiting for the person to reply, it kind of has a Skype-looking feature, that whenever the person is typing, you will actually get a "dot dot dot" (...) on the bottom left, right above the keyboard.

The option in settings to send messages as SMS "when iMessage is unavailable" simply means if you are using the Sprint/Google Voice combo mentioned above, or if the person you are messaging does NOT have the IOS 5+ software (meaning they can NOT receive iMessages) then the phone will send a normal text message (carrier rates apply).

Hope this helped out. If I figure out anything else, I'll edit this later.