IP phones in hotel rooms are not all that uncommon now a days. Many hotels are putting in IP when they build out a new property. Legacy hotels will probably continue to use analog, or we are even seeing some customers using PhyBridge's product (works well, installed it a few different times).
If you look, most of the "traditional hotel telephone manufactures" are now producing an IP variant of their analog phones. They look identical, however they are pure SIP. We've installed those and they work very well.
I would say more Mitel hotel customers go IP in the rooms then our Avaya hotel properties do. We don't have a lot of customers that request IP Office for hotels, more request Mitel from us for that. On the Mitel side we typically install SIP hotel phones in the regular rooms (or Mitel's wireless hotel set - SIP based, design specifically for hotel rooms/cruise ship cabins), and then the Mitel 5360 IP phones in business, executive and suites. That's a pretty common setup now a days for a hotel (for us anyways).
Brand/flags haven't standardized on SIP/IP yet, however they do require a IP/SIP compliant PBX. Most flags have identified SIP-based room phones they will allow. They can still go analog if they want (as long as it meets the flag/banner standards issued). SIP-based hotel room phones have been on most flag's standards for a couple of years. Just so I'm clear, when I say "standards" I'm referring to the document most banners/flags issue each year saying which products/manufactures are permitted for use within the hotel that operates under their particular banner/flag.
