Sorry if this is off topic but I really don't know of a better place to ask this question. I had a customer with a couple of locations that have Mitel SX200 PBXs. Their voice vendor asked us to hand them a Voice T1 out of our CPE which is an Adtran TA904. They told us that the T1 needed to be configured as D4/AMI. After the install the customer experienced dropped calls and the vendor could only really say that everything worked find with the previous carrier so it has to be our problem. After a day or so of trying to figure out the problem I switched to D4/B8ZS because I was out of ideas. As soon as I switched to D4/B8ZS the errors stopped and the calls stopped dropping. I questioned the vendor again and he swears that their side is set for D4/AMI and now he thinks it much be a glitch in the Adtran. I think it's either the vendor didn't look at the config or it's something strange in the Mitel. Has anyone else come across this before? Richey