We have an IPx 500 with a PRI and are having weird and intermittent echo issues. No issues with internal calls, only SOME toll free numbers have the echo and once in a great while other numbers will have the echo. The toll free numbers that echo, do it everytime you call. I had my telco looking into it a few times with no luck, the vendor says there is nothing in the Tadiran to look at. I know some PRI cards for building your own PBX come with echo cancellation. I guess the Tadiran has nothing like this?