3 ms·

Note that the “delivered” indicator in iMessage just tells you when it was delivered to the network, and not the recipient. It’s entirely possible to still lose

Note that the “delivered” indicator in iMessage just tells you when it was delivered to the network, and not the recipient. It’s entirely possible to still lose the message after it gets delivered to the network. The only way you could know for sure if the recipient got the message is if they have read receipts turned on, so that you know when they’ve actually read the message. And plenty of people have had problems where they took their cell phone number with them to a non-iPhone device but can never receive iMessages, but they also can’t receive regular SMS messages to that number. There still be plenty of dragons here.

davidajackson 7y ago
> Note that the “delivered” indicator in iMessage just tells you when it was delivered to the network, and not the recipient. It’s entirely possible to still lose the message after it gets delivered to the network Is there any reason to believe that in the USA for example iMessages would be 'dropped' at a higher rate than SMS? Put another way, is an iMessage 'delivered' less valuable than an SMS 'delivered'? Curious to hear your thoughts.
- bradknowles 7y ago
  There is a low limit to the maximum size of an SMS message. Small enough to fit the entire thing plus all meta data easily into a 512 byte UDP packet. Sure, UDP is unreliable, but everyone knows that and you build additional reliability mechanisms on top of that. The SMS protocol is different, but still shares a lot of similarities. With iMessage, the messages themselves can be much larger, and the larger the message the more likely it may run into packet fragmentation which could easily result in it being silently lost down the road. With SMS, once the network has accepted the message, I think you have a higher probability that it will actually reach the recipient. Another factor here is cost — precisely because you pay for SMS messages, the carriers are going to aggressively maximize the delivery probability, because they don’t want to lose a single red nanocent. But iMessage is free, so why should anyone care to optimize that for maximum delivery probability? Then you also run into the other issues noted above, e.g., where someone previously used a given number with an iPhone and then moved to Android. The number is still detected as being iMessage capable, but you can’t actually send an iMessage to them on Android. I guess all I’m really saying is TANSTAAFL — There Ain’t No Such Thing As A Free Lunch. Oh, and be careful what you optimize for. You may optimize yourself out of a job.

davidajackson 7y ago

> Note that the “delivered” indicator in iMessage just tells you when it was delivered to the network, and not the recipient. It’s entirely possible to still lose the message after it gets delivered to the network Is there any reason to believe that in the USA for example iMessages would be 'dropped' at a higher rate than SMS? Put another way, is an iMessage 'delivered' less valuable than an SMS 'delivered'? Curious to hear your thoughts.

bradknowles 7y ago
There is a low limit to the maximum size of an SMS message. Small enough to fit the entire thing plus all meta data easily into a 512 byte UDP packet. Sure, UDP is unreliable, but everyone knows that and you build additional reliability mechanisms on top of that. The SMS protocol is different, but still shares a lot of similarities. With iMessage, the messages themselves can be much larger, and the larger the message the more likely it may run into packet fragmentation which could easily result in it being silently lost down the road. With SMS, once the network has accepted the message, I think you have a higher probability that it will actually reach the recipient. Another factor here is cost — precisely because you pay for SMS messages, the carriers are going to aggressively maximize the delivery probability, because they don’t want to lose a single red nanocent. But iMessage is free, so why should anyone care to optimize that for maximum delivery probability? Then you also run into the other issues noted above, e.g., where someone previously used a given number with an iPhone and then moved to Android. The number is still detected as being iMessage capable, but you can’t actually send an iMessage to them on Android. I guess all I’m really saying is TANSTAAFL — There Ain’t No Such Thing As A Free Lunch. Oh, and be careful what you optimize for. You may optimize yourself out of a job.