I use PM# based CT1 and have had good luck. Out of about 1000 diffrent
users calling into them, 3 had problems. One was an Intel 14.4 modem,
another I can't remember and the third is a Supra 28.8 modem upgraded to
33.6. The Supra is most likely broken since other identical Supra models
work fine.
PRI lines here are close to double CT1 prices.
-- IanSmith