Subscriber
Access Network
Transport Network
Core Network (PSTN / SS7)
Service Network
Telephone
Subscriber A (Calling)
Cabinet / DP
Distribution Point
DSLAM / OLT
Access Multiplexer
Metro / Backhaul
Aggregation Transport
Class 5 / LE
Local Exchange
STP
Signaling Transfer Point
SCP / SDP
Service Control Point
Gateway
Trunk / Media Gateway
IN Service
Intelligent Network (SCF)
Destination Phone
Subscriber B (Called)
Local Loop
Access Line
Trunk
Backhaul
SS7 / MTP
INAP / TCAP
Core Link
Service Link
Destination Line
① Subscriber
② Access
③ Transport
④ Core
⑤ Service
READY Click "Start Flow" or "Next Step" to trace the PSTN Call flow.
📡 PSTN Call Flow Log
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