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In terms of the technical details the IdP would generate the one-time use token using a secure random number generator and store the token in the IdP clustered data store. A pluggable API would be used to send the SMS. The IdP would ship with an implementation that uses the Short Message Peer-to-Peer (SMPP) or Simple Network Paging protocol , a standard protocol supported by most (SNPP) protocol, depending on which protocol was supported by the majority of SMS gateways.