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RV340 firmware upgrade V1.0.03.20 reproducibly breaks VOIP telephony

H. Erne



last night our RV340 installed the firmware V1.0.03.20 (from with the effect, that incoming VOIP channels stopped working. From looking at the release notes nothing indicates that there have been changes in this area.


Roling back to V1.0.03.19 makes everything work again, rolling forward to V1.0.03.20 breaks VOIP again. So this seems to be a reproducible issue...


Can anybody help or provide more details on what has changed in the firmware?



3 Replies 3


Thanks for the heads up!  I have a RV-340 and was going to install this firmware at my next maintenance. I have two WFH users who need until this is answered...I'm not updating!

Martin Aleksandrov
Cisco Employee
Cisco Employee



Is your VoIP SP a SIP provider? If so he might use SIP-proxy with no server-side NAT solution. In that case, you should enable SIP ALG in your RV firewall settings. However, in most of the cases, SIP ALG should be disabled so try both ways. In your non-working scenario, you can also do WAN packet capture on the RV to see what is the reason for the VoIP disconnection. You can share the outcome so we can further analyze. Step-by-step guide of how to do WAN packet capture you can find at: 




Hi Martin,


thanks for the suggestion, but the setup has been working well with the previous firmware versions. So I guess either there was a huge security hole fixed with the current firmware (although undocumented and not in the release notes) or the firmware actually breaks things.


I have opened a ticket with Cisco support, but so far no valuable feedback (other than resetting the configuration before upgrading - and guess what the official procedure for restoring the configuration is: YES, you have to write down your old configuration and configure everything from scratch manually).


I guess that I will keep the "old" firmware until Cisco support provides some more insights - I will post again here. According to the release notes, there is nothing security relevant (for me) in the latest update, so better a working firmware than the newest one...


Best regards,



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