welcome to the world where no one really knows the hosp feature, mostly due to mitel having 90 percent of the small hotel customer base.. that is a serial link, so your looking at just copper.. you may have a pair of short haul modems extending it out to a term.. those can flake out, or the daughter board they connect to.. a up and down problem like that is usually layer one, copper or at worst the analog style i/o port.. this isn't much help but may be all you get, i've only installed a few of those and it's been forever
john poole
bellsouth business
columbia,sc