My read was that the SIP protocol was just less well suited to a mobile environment. Not merely that long-lived connections are bad, but that it would be inappropriate to use a long-lived connection that requires keepalive packets or loses user data every time the user goes underground (SMS queues up for delivery when the connection is re-established, and APNS will at least deliver the most recent push). Technically even the SMS solution requires a persistent connection, it's just the device's persistent connection to the cell network, which is presumably better tailored for the mobile use case.
SIP is unsuited for any environment. It is a disgrace of a protocol and a hot mess at that. At it's foundation it was designed to be 100% NAT incompatible and since it's inception bandage has been added to address this and it's other shortcomings. Faster we replace it with some/any alternative the better. From protocol design standpoint, SIP is so bad that it makes H.323 feel like a sane VoIP protocol (which it isn't). </rant>
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My read was that the SIP protocol was just less well suited to a mobile environment. Not merely that long-lived connections are bad, but that it would be inappropriate to use a long-lived connection that requires keepalive packets or loses user data every time the user goes underground (SMS queues up for delivery when the connection is re-established, and APNS will at least deliver the most recent push). Technically even the SMS solution requires a persistent connection, it's just the device's persistent connection to the cell network, which is presumably better tailored for the mobile use case.
SIP is unsuited for any environment. It is a disgrace of a protocol and a hot mess at that. At it's foundation it was designed to be 100% NAT incompatible and since it's inception bandage has been added to address this and it's other shortcomings. Faster we replace it with some/any alternative the better. From protocol design standpoint, SIP is so bad that it makes H.323 feel like a sane VoIP protocol (which it isn't). </rant>