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This document uses an example trace to document the full processing of an inbound telephone call from call set-up to call termination.
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In the interests of readability, the trace has been shortened to a few relevant sections. Traces usually contain some components that have to be skipped as they are not relevant to the analysis. |
Scenario:
- A LANCOM VoIP router is connected to a Deutsche Telekom line with a SIP trunk.
- Connected to the LANCOM router is an ISDN telephone that has been assigned the MSN 123412. The # character is a wildcard for any number of digits, which is why the user 1234# is used when dialing MSN 123412.
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1) The provider sends an INVITE packet to the LANCOM router.
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You can find for |
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the INVITE packet in the trace by searching for the character string INVITE sip. The INVITE packet is a part of the SIP-Packet trace. |
The following important parameters are included in the INVITE:
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4) The target number 123412 (see step 2) passes through the Call Routing table. The phone number does not match any call route, so the number is forwarded to the user table, where a match to an ISDN user is found (see scenario).
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For more information on the Call routing table, see this knowledge base article. |
5) The LANCOM router sends a SETUP to the ISDN telephone. The SETUP indicates the establishment of the ISDN connection.
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You can identify this packet precisely by searching the trace for SETUP. The SETUP packet is a part of the D-channel-dump trace. |
The following important parameters are included in the SETUP:
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