Short Message Service (SMS) of mobile cellular networks is frequently
used in Machine-To-Machine (M2M) communications, such as for
telematic devices. The service offers small packet sizes and high
delays just as other typical low-power and lossy networks (LLNs),
i.e. 6LoWPANs. The design of the Constrained Application Protocol
(CoAP), that took the limitations of LLNs into account, is thus also
applicable to other transports. The adaptation of CoAP to SMS
transport mechanisms is described in this document.