IP trunks online vs registrations - why not equal

I have setup a system with 8 iax trunks (no sip trunks). All require registration with the ITSP, and ‘iax2 show registry’ confirms all 8 are registered.

In the freepbx console i see 8 trunks registered but only 6 online. I have not set qualify= for any trunks. Why would the two values differ?