add SGs / CSFB related dot + msc files
Those graphs + message sequence charts are not yet used by any
of our manuals, but they should become used by the OsmoMSC user
manual once SGs interface support is added.
Related: OS#2583
Change-Id: Idfd3a66c18131b5458d183b8e66f62eaaab65991
diff --git a/doc/manuals/images/sgs-mt_call_idle.msc b/doc/manuals/images/sgs-mt_call_idle.msc
new file mode 100644
index 0000000..b3cff3c
--- /dev/null
+++ b/doc/manuals/images/sgs-mt_call_idle.msc
@@ -0,0 +1,17 @@
+msc {
+ hscale=2;
+ UE, ENB [label="eNodeB"], BSS, MME, VLR [label="MSC/VLR"], PSTN;
+
+ VLR <= PSTN [label="ISUP IAM or SIP INVITE"];
+ MME <= VLR [label="SGsAP PAGING REQUEST"];
+ ENB <= MME [label="Paging"];
+ UE <= MME [label="Paging"];
+
+ UE => MME [label="Extended Service Req"];
+ MME => VLR [label="SGsAP SERVICE REQUEST"];
+ ENB <= MME [label="Initial UE Ctx Setup"];
+
+ UE => BSS [label="Paging Response"];
+ BSS => VLR [label="COMPL L3 (PAGING RESP)"];
+ UE <=> VLR [label="Normal 2G Voice Call"];
+}