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Another issue apart from addressing is that all the SMS related logic resides in the SMSC and rest of the network sees the traffic as opaque payload. The artic
by dfox 8y ago
Another issue apart from addressing is that all the SMS related logic resides in the SMSC and rest of the network sees the traffic as opaque payload.
The article glosses over how the resulting message structure is actually sent over the radio interface and the SS7 network. In all it involves establishing (somewhat TCP-like) connection between your phone and SMSC across the signalling paths. The fact that this process is somewhat involved and consumes significant amount of radio resources is probably at least partially the reason why SMSes aren't particularly cheap.
On the other hand on native LTE sending or receiving SMS could in theory consist of two UDP packets, but I'm not sure how widely is this deployed.
- voltagex_ 8y agoSMS over LTE is RCS [1], isn't it? I'd be happy to use it but my carrier/phone manufacturer have decided to limit the RCS apps I can use. 1: https://en.wikipedia.org/wiki/Rich_Communication_Services https://en.wikipedia.org/wiki/Rich_Communication_Services
- fyfy18 8y agoI thought SMS was built on top of the existing GSM signalling protocols, and so is effectively free to carriers. The bandwidth costs of a few hundred byte message are nothing compared to streaming a video or a phone call. The only reason why carriers charge for SMS is because they can.
- bestham 8y agoAn SMS is sent in the GSM SACCH (Slow Associated Control Channel), that channel is normally used for timing information (how far away the handset is from the cell tower and the power control of the handset). Since SMS is not a real time application, they are virtually free. The phone will wait until it is possible to send. This and congestion on the SMSC is why SMSes sent on New Years eve often are delayed.