TDM 400P card reboots Arris TM722 phone service

My Digium Wildcard TDM400P REV I Board 1 card has been working great. Today I switched service on one of my 4 phone lines to which provides cable based phone service with an Arris TM722 device. When the TDM400P card is plugged into the new phone service (that is, into the TM722 device which is working with 3 test phones), it causes the Arris TM722 device to fail and require a factory reset. Ooops.

Clearly my assumption about POTS compatibility was wrong. Is there documentation that I missed?

What could the TDM400P be doing to cause such a problem? How do I fix it?


The TDM400 was marked End of Life and replaced by the TDM410. Digium no longer performs support or provides bug fixes for the TDM400P.


I have a TDM04B on the shelf. When I bought it, I understood it to be a replacement for the TDM 400P. Is it likely to cause issues with the Arris TM722?

The “TDM04B” SKU was a bundling of the TDM400P and four FXO modules.

The TDM410 bundlings are all like: TDM4XYZ. X is # of FXS modules. Y is # of FXO modules. Z is B for no DSP Echo Cancel or E for yes DSP Echo Cancel

Since I only need the card to dial in and out on POTS lines, FXO should be adequate for my needs, right? Maybe the FXS in my 400P card is generating ringing voltage or dialtone or something that is confusing the Arris TM722. So the TDM04B which does not generate dialtone, ringing voltage, etc may actually “play nicer” with the Arris TM722. Does it seem like a good test?

What are the issues involved in switching from the 400P to the 04B? How do I reconfigure the zaptel subsystem? Does asterisk need to change as well?

If you’re terminating a line from the telco, then you just need FXO.

The TDM410 uses the wctdm24xxp driver instead of the wctdm driver. Otherwise, configuration is the same.