We have been having trouble making outgoing calls intermittently on one of our PRI's, the CO would send a reject message indicating the channel was not available, but it showed idle in the switch. Callers would get 'release and try again' so I disabled the dch and the loop and the other PRI picked up the traffic OK. Our vendor came today and wanted to swap the tmdi card that the bad loop was riding. He verified that the dch and loop were disabled and then pulled the card. When he seated the new card the switch went INI, should he have done something else? Tech support said that what he had done was correct but that this will happen one out of a hundred times. Could we have done anything to prevent this?