We've been having the same issue here with specific phone systems (around 50% calls with no caller-id even if we can see the callerid on the fluke testset):
- Cisco UC 560
- Avaya IP Office
We're delivering analog lines through a Netvanta 6310 with quad-fxs and octal-fxs cards.
No solution so far.. we've switched one Avaya to SIP trunks as a workaround. We'll prolly open a case regarding this. Will update if a fix is found.
Analog caller-ID is sent by Bell 202 1200-baud modem tones between the first and second rings. Possible intermittent failure modes may be timing (tone burst too soon after first ring so that AC ring voltage swamps the receiver) or level or twist of the modem tones. So I'd look at any configuration settings that might affect that. I'm not really familiar with the TA600 series, more of a TA900 guy. You might also play with impedance settings and TX levels on the FXS ports.
How old are these units? I have some VERY early notes on the TA900 that include the following, slight possibility it might be relevant:
"Adtran recently swapped power supplies in 904 because voltage to chip set responsible for generating caller-id was off by 2V. Supply was in-spec per manufacturer of chip set but they were getting intermittent caller ID. Remanufactured power supplies to bump up 2V to get into range; really big hassle."