I would guess that you have a HW/SW problem purtaining to your TDS card/s. If this is an Option 11 then you have this problem with your SSC card. I would STAT your TDS's and check to see if they are idle or busy. It may just be a capacity issue (IE: phone set to tds ratio is not correct). If this is an Option 11 and they show disabled, you MAY (rarely) be able to enable your TDS's by using LD 34. If not the only other way to enable these in an Option 11 is to INI. If this becomes an ongoing problem then I would suggest replacing the SSC card. If this is a nt,st,hybrid,21,51,61,71,81 then I would suggest trying to find logic to the phones that have this issue (IE: on the same network group,same shelf). Once you get this or if you see no rhyme to it then start looking at you TDS's . If you find that it happens on Network Group 0 Shelf 1 Loop 20, then I would look at the TDS's in that Network Shelf, if any. If you donot have any TDS's in that Shelf then I would look at the other shelf within that Group. If no TDS's are in there the I would look into any TDS cards in anohter network group. You should find either a slow responding card (IE: card that takes longer to return ok code) or you will find a faulty card. In this case I would disable the Conf/TDS pack and test to see if it is this particular card (assuming you have more than 1 Conf/TDS pack in your system). Let me know what you find from here. There are numerous other steps to track it to either the card or network slot or to see if it is a capacity issue. Good Luck