| CPC H04W 60/00 (2013.01) [H04W 8/08 (2013.01); H04W 8/18 (2013.01); H04W 12/06 (2013.01); H04W 40/04 (2013.01); H04W 48/18 (2013.01)] | 9 Claims | 

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               1. A method performed by a first access and mobility management function (AMF) in a communication network, the method comprising: 
            receiving a first registration request message from a user equipment (UE); 
                determining that the first AMF is unable to serve the UE and the first AMF is unable to directly communicate with a second AMF, wherein the second AMF is a target AMF for rerouting; and 
                sending a registration accept message to the UE in response to the first registration request message, 
                wherein the registration accept message includes reroute assistance information including a 5G-global unique temporary identifier (GUTI) encoded for an AMF set including the second AMF, and 
                wherein the 5G GUTI comprises at least one of an AMF-Set identity (ID) in a globally unique AMF ID (GUAMI) being set to an AMF ID of the second AMF, an AMF pointer set to 0xFFFFFF value or a reserved value, or a serving temporary mobile subscriber identity (S-TMSI). 
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