digraph G {
rankdir=LR
labelloc=t;

	msc [label="MS/BSS/MSC"]
	subgraph cluster_proxy {
		label="HLR Proxy"
		proxy_mm [label="Proxy Mobility Management FSM",shape=box3d]
		proxy_home [label="Proxy to Home HLR FSM",shape=box3d]
		proxy [label="GSUP Proxy"]
		proxy_mm -> proxy_home [constraint=false,dir=both,label="(FSM events)"]
	}
	hlr [label="Home HLR"]

	msc -> proxy_mm [dir=both,label="MM related GSUP\n (immediate response\n if possible)"]
	proxy_home -> hlr [dir=both,label="MM related GSUP\n (delayed)"]

	msc -> proxy -> hlr [dir=both,label="non-MM GSUP",style=dashed]
}