The faxes aren't arriving in my email. For one of the lines, the client's fax service reports a successful transmission, but I didn't receive it and there's no entry in my Sonic fax log. For the other it reports failure with no further details.
I've verified that both lines ring a fax tone when I dial them.
I see this has been posted about in the forums before, but the response has been that Lab features aren't supported. Since there's still a need for faxing documents, maybe it's time to get faxing out of beta and fix any bugs.