Dialstring parameter for the Session Initiation Protocol URI
RFC3966 explicitly states that TEL URIs may not represent a dial string. That leaves no way specify a dialstring in a standardized way. Great confusion exists with the SIP URI parameter "user=phone", and specifically, if it can represent a dial string. This memo creates a new value for the user parameter "dialstring", so that one may specify "user=dialstring" to encode a dialstring as a SIP or SIPS URI.