Here's an email that has been floating around about ISDN problems with AT&T
If you use ISDN, or you have clients or Talent that use ISDN, please forward this to them, and tell them to show it to whoever handles their phone service. For about two weeks, some of us have been experience some real problems connecting via ISDN to certain areas of the country. Southern CA is the worst for me. I called Telos, and they told me I am not alone. It is a severe problem in some areas, and it is only affecting those who have long distance service through AT&T. Telos says they can no longer recommend anyone use AT&T for ISDN long distance, and to switch to Sprint or MCI as soon as possible. (Telos tech support is 216.241.7225 if you want to ask them about it.) It may take up to two weeks to make this change, but in the meantime there is a simple workaround. To force your ISDN session to go through Sprint, simply add the numbers 1010 333 to the ISDN dial up numbers. For instance, if you normally dialing 1-555-555-1212 and 1-555-555-1213, instead just dial 1010 333 1-555-555-1212 and 1010 333 1-555-555-1213. I have done this several times, and my "problem" clients have as well, and it seems to work perfectly. One more warning that we all need to make some long-term plans for the demise of ISDN. It is 30-year-old technology, and a local AT&T technician told me many of the circuit boards in the local ISDN routing network are failing regularly from age.
What are your thoughts?