We had a similar experience, but with an ACS and AT&T. The customer didnt change lines or anything and all of a sudden CID stopped coming in. They called AT&T the tech came out and showed them it worked on a CID box. I came out and said I hear the tones but it should display. So I happened to have an IPO 500 that was going to be installed at another customer, I plugged it into a line and watched System Status and the call came in with a + in front of the number. I told them AT&T changed how the number came in. They called AT&T and told them, the tech then came out again and showed them how a brand new CID box worked. So I went out and bought an analog AT&T CID capable phone from Best Buy and tried it, and it didnt work lol. I left the phone there for the tech and a few days later the customer called and said the tech came back used that AT&T phone and it didnt work then after an hour or so it started working again.
