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Error pattern:

The LCOS firmware of a LANCOM VoIP router has been updated to version 10.42. After the update, telephony problems occur if a SIP PBX is used in the scenario.


Possible Cause:

In LCOS 10.42, the standard value for UDP aging was changed to 120 seconds. It can happen that the new standard value is not automatically adopted during the update and that a value that is too small is used.


Elimination of behavior:

1. Open the configuration of the LANCOM router and switch to the menu IP Router → Masquerading.

2. Change the value of UDP aging to 120 seconds.

3. Write the configuration back to the LANCOM router.

The telephony problems should be resolved after this change. If the behavior does not change, please contact LANCOM support.