New iMessages not added to a new/restored device

[Commodore]

I'm not sure whether this is yet another iMessages bug, but it can be annoying when it happens. Here are my observations:

-If you have an iDevice offline for a day or two, and use iMessages on another one, you will get all those messages on the offline device once you put it back online. Make sense. So far so good.
-However.... if you restore from a backup to a new iDevice, that new iDevice won't receive all the messages that were "created" in the interim period (between the time of creation of the original backup and putting the newly restored device online). It just receives the new ones from then on.

I suppose it's probably connected to the devices' hardware unique ID. Is there any way to force the new device to "re-download" missing messages?

 

[twerppoet]

iMessages remain on Apple's servers for a limited time. If the server knows that it's waiting to deliver a message to a device, it will probably hang on to it a bit longer, but even then there is a limit.

This means that when you've restored a device there is no list of old messages on the server for your device to download. It will only get the newer messages, the ones that have been sent since the device connected back to your account and iMessages was enabled.

I's a similar story with SMS, only that depends on your carrier.

So, basically, the only log of old messages you have are the ones stored on your device(s). There is no way to recover them from Apple's servers, because they are not there.

Depending on how you want to look at it, this is actually good news. If for some reason the NSA demanded all iMessage traffic from the last week, month, year; even if Apple had to comply they could't hand over more than a day or two at most. That's on top of the encryption, which is done in such a way that Apple doesn't have the decryption keys.