I have a CIX670 system which shows me the number of basic ports licenses, but it does not show how many are used, that field is empty. What is the best way to figure out how many basic ports are used?

The older BCTU1A processors with version 3.10 software only show the licenses installed, not the number n use.

Unless you plan to upgrade the processor, the only way I know to find the ports in use is to count all the extension ports and all the trunks. A BIPU extension would count as a basic extension , but an LIPU extension only uses an IP port.

If the number of used ports are close to the licensed ports (which is usually the case), I sometimes try to add extensions until the system pops up with an error.

If you have an open slot you could assign a BDKU and try to add 8 additional extensions. Just remember the ones you added so you can undo the new extensions and card.

Looks like we are running 2.21, I will try your suggestions.
Does the PRI trunk count towards basic ports in use?

If we need to upgrade the processor will we be able to load our backup with the older version of the software?

Yes, the PRI counts as basic port. A PRI typically has 23 B channels which uses 23 basic port, but you can count the actual B channels in use in case not all 23 channels are used.

You can restore a backup to a new processor. If you have more then 64 basic ports, you can also move over your existing licenses to a new processor, but Toshiba will want the old processor returned, plus a scrap fee.