This Recommendation defines the error codes that are used in the core ITU-T H.248.1 protocol. It lists the error code number associated with the error code name. It then provides a definition of when the error code is to be used and if the error code is defined in a package. It also provides an indication of what text may be included in the error text descriptor to allow further interpretation of the error code. Clause 4.2 provides these details. The normal actions for failed transactions and commands apply as specified in clause 8 of [ITU-T H.248.1]. Packages may define error codes not documented in this Recommendation. The IANA registry should be consulted for the complete list of error codes.

Error codes marked as "not used" are historical in nature and are for informational purposes only. These error codes should not be used.

This Recommendation also defines the service change reasons that are used in the core ITU-T H.248.1 protocol. It lists the service change reason code associated with the service change reason code name. It provides a definition of when the service change reason is to be used. It also provides an indication of what text may be included in the service change extension to allow further interpretation of the service change reason. Clause 5.2 provides these details.