Miscellaneous bits and bobs from the tech world

Fixing a SPA112 registration failure (Tomato/SPA112/

9/17/2021, 11:15:07 AM

Since replacing my router with an Asus RT-AC68U1, I ran into an odd issue where my VoIP phone no longer registered with my provider VoIP.ms1.

I didn't clue in immediately that it was due to the router (and firmware) change, and I was about to reach out to the support team but decided to check their FAQ2 as it was suggested I do so prior to starting the live chat session.

As it turns out, there is an incompatibility with the Tomato firmware and the Linksys/Cisco SPA1121 I use.

To resolve,

  1. Navigate to your Tomato router at and log in.
  2. Navigate to Advanced > Conntrack/Netfilter
  3. Under "UDP Timeout", change "Unreplied" to 10 (it was set to 30 for me)


After waiting a couple seconds for the SPA112 to attempt reregistration, I was back in business, dial tone and all!

Kudos to the team for noting this on their wiki.


1 This is a referral code. Clicking on it and buying the product helps me maintain this site, but it's perfectly okay if you don't, either :)

2 I will state now that this is probably one of very few times when checking the FAQ actually led to a solution.