| CPC H04L 45/02 (2013.01) [H04L 45/34 (2013.01)] | 18 Claims | 

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               1. A method for inter-service communication proxy (SCP) routing, the method comprising: 
            at a first service communication proxy (SCP) associated with a first domain, the first SCP including at least one processor: 
                receiving, by the first SCP, a first request destined for a producer network function (NF); 
                  determining, by the first SCP, that the first request lacks a list comprising a sequence of domain identifiers identifying, in sequence, domains for routing the first request to the producer NF; 
                  determining, by the first SCP, a domain associated with the producer NF; 
                  determining, by the first SCP and using the domain associated with the producer NF, the list comprising the sequence of domain identifiers identifying, in sequence, the domains for routing the first request to the producer NF; 
                  adding, by the first SCP and to the first request, the list comprising the sequence of domain identifiers identifying domains for routing the first request to the producer NF; 
                  determining, by the first SCP and using the list comprising the sequence of domain identifiers identifying the domains for routing the first request to the producer NF, a second SCP for routing the first request; and 
                  sending, by the first SCP and to the second SCP, the first request including the list comprising the sequence of domain identifiers identifying the domains for routing the first request to the producer NF; and 
                at the second SCP: 
              receiving, by the second SCP, the first request; 
                  reading, by the second SCP, the list comprising the sequence of domain identifiers in the first request; 
                  using, by the second SCP, the list comprising the sequence of domain identifiers to determine a next hop for the first request without contacting the NRF; and 
                  forwarding, by the second SCP, the first request to the next hop. 
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