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) [RFC7252], 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.