The present document clarifies recommended measures which may be adopted by 3GPP infrastructure utilising GSM or GERAN as access network to enable inter-working to be obtained between network and various User Equipment (UE) implementations of the 3GPP specification. The objective is to obtain compatibility without changing the consolidated set of specifications. The present document describes the recommended changes to the infrastructure to cater for specific faults within some types of UE. The lifetime of the herein described measures together with their potential impact on optimal network performance is out of the scope of the present document.