It strongly sounds to me like defective hardware. As I recall the PoE function on 48-port switches has two power supplies, each supplies 24 ports.
It could also be that you've exceeded the power limit for the box. If you configure some or all of the first 24 ports as "power inline never" do the second 24 start to work? It could also be a situation of PoE negotiation failing. The following article, although quite dated now, may give some insight. https://impulse.net/blog/cisco-switch-power-deny-issue-with-polycom-phones/
Thanks for the great information and advice Jayh. I'm very busy today, but I was wondering if the Cisco command "Show Power Inline" works on Adtran switches? That command would show me the PoE power usage (At least on a Cisco).
I should also mention that if I unplug one of the currently plugged in PoE cables going out to a VoIP phone (one that is already working on ports 1-24) and try to plug it into one of the other ports on the switch (Ports 25-47) it still will not get power. Because of this, it seems to me that even if the switch's power was at full capacity, then unplugging a phone from port 17 (thats working) and plugging it into port 27 should work. Same amount of power, just swapping ports..right? I'm still thinking that maybe it is a hardware issue where the power supply for PoE to the 2nd half of the switch is malfunctioning or broken.
When I get time later I will try and get upstairs to the data closet where the 48-port switch is located and look into the "Power Inline Never" and see if that opens up any ports on the 2nd half of the switch.
I read through the link you provided, but I don't think that is my issue because the digium phones that I use are pulling 6 watts and there are no power setting on the phones.
I really appreciate you taking the time out to respond and will let you know how everything works out.
Yes, "show power inline" works as expected, as do most "Brand C" commands, except BGP. Adtran BGP syntax is weird. The Polycom issue was quite a gotcha at the time.
I suspect you have a bad power supply. It's tough to design high power supplies that fit into a 1U chassis with decent cooling, and I seem to recall that Adtran actually has three supplies in that box to distribute the load. One is for the logic of the switch itself and two 48V supplies, one for each half of the PoE.
Thanks for your help Jayh, the power supply for the 2nd half of the switch must be dead. I did what you suggested and to no avail. No matter what I do, I cant get PoE to work on that side. There are 7 switches in that data closet, so I did a "sh power inline" on the other switches and moved non-PoE lines over to the side that nots working for PoE...just enough so that I could remove that 24 port switch that I needed on the 3rd floor. I have not removed it yet as I'm making sure that no employees were affected by the swap.
Really appreciate you taking your valuable time to answer my questions.