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Yes, sms is "actually push" all the way down to the transport layer. As far as I know, this is still what push notifications are built upon for an idle/sleepin

Yes, sms is "actually push" all the way down to the transport layer. As far as I know, this is still what push notifications are built upon for an idle/sleeping device. Carrier infrastructure knows which tower you last connected to, instructs that specific tower to broadcast a message telling your phone to wake up and fetch the remaining 80% of the notification content (the sms bit is usually just enough for your device to learn the UUIDs of the notifications)

nothrabannosir 1y ago
iOS or Android push notifications (can) use SMS for notifying the client that a new message is available ? That’s lovely. Do you have any links or any keywords to find more ? All I can find online is that iOS uses TCP (XMPP in fact :o TIL. )
- PinguTS 1y ago
  No, Apple push cannot use SMS/Text. You need a cell modem to have working SMS/Text. Except the phone itself, most of the devices have no cell modem. Then Apple would need to keep a directory of all the cell phone numbers, because that is the way how the cell modem is addressed.
- yencabulator 1y ago
  It wasn't really SMS, it was another message type riding on top of the same lower-level protocol called SS7. But it seems that's no longer in use and it's all just TCP/IP now. (Said differently, the radio firmware got good enough that it doesn't need a special "wake up" packet anymore, it can recognize a packet to itself in a low power state.)
yencabulator 1y ago
> As far as I know, this is still what push notifications are built upon for an idle/sleeping device. I thought so too, but can't find any evidence for it anymore, all I can find is mentions of the phone keeping a TCP connection alive and then some device driver level tweaks to make that power efficient. I think the older GSM-specific wakeup mechanism might have died when iPhones stopped being carrier-specific.

nothrabannosir 1y ago

iOS or Android push notifications (can) use SMS for notifying the client that a new message is available ? That’s lovely. Do you have any links or any keywords to find more ? All I can find online is that iOS uses TCP (XMPP in fact :o TIL. )

PinguTS 1y ago
No, Apple push cannot use SMS/Text. You need a cell modem to have working SMS/Text. Except the phone itself, most of the devices have no cell modem. Then Apple would need to keep a directory of all the cell phone numbers, because that is the way how the cell modem is addressed.
yencabulator 1y ago
It wasn't really SMS, it was another message type riding on top of the same lower-level protocol called SS7. But it seems that's no longer in use and it's all just TCP/IP now. (Said differently, the radio firmware got good enough that it doesn't need a special "wake up" packet anymore, it can recognize a packet to itself in a low power state.)

yencabulator 1y ago

> As far as I know, this is still what push notifications are built upon for an idle/sleeping device. I thought so too, but can't find any evidence for it anymore, all I can find is mentions of the phone keeping a TCP connection alive and then some device driver level tweaks to make that power efficient. I think the older GSM-specific wakeup mechanism might have died when iPhones stopped being carrier-specific.