In American English, we usually employ the term "host provider" or "webhost". Of course, hosting provider works well too. :)

I cannot ascertain what WLRH is, as google turns up essentially nothing but the proz entry and a radio station, but WLR is "wholesale line rental", a wholesale voice line access service offered by incumbent telephony providers to resellers. Everything I can find says that this is voice level service only, not the very high speed raw Internet access lines for hosting providers. I spent 15 years in private (PBX) telephony, so this sounds familiar. :)

http://www.entagroup.com/enta-history.htm

Entacall provided Wholesale Line Rental (WLR) in the form of PSTN and ISDN lines, marketing numbers, Carrier Pre-Select (CPS) and additional telephony services such as audio conferencing and automated TPS.

http://stakeholders.ofcom.org.uk/telecoms/groups/close-group...

Wholesale line rental (WLR) is a product that BT is obliged to provide to other Communications Providers. It enables other Communications Providers to offer both line rental and calls to end-users over BT's local network.

http://www.openreach.co.uk/orpg/products/wlr/wlr.do

Various references to Communication Providers, or CPs, that resell both analog and digital voice services.

http://www.gammatelecom.com/wholesale_line_rental.asp

Since the introduction of Wholesale Line Rental, Gamma Telecom has been able to provide our resellers with the same line rental solutions as BT but with flexible pricing and service criteria.

http://it.wikipedia.org/wiki/WLR

WLR - wholesale line rental, servizio che consente di utilizzare un operatore telefonico alternativo al fornitore dell'accesso non mediante distacco della linea, ma perché quest'ultimo prende a nolo la linea stessa dal fornitore dell'accesso a condizioni d'ingrosso...

PSTN: Public Switched Telephone Network, or standard analog lines.

ISDN 2 or 30 is either a 2 channel direct subscriber line or a 30 channel E1 Integrated Service Digital Network circuit. True, these can carry digital subscriber data as well as digitized voice, but in general this would fall under the rubric of telephony services.

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Note added at 16 hrs (2010-10-12 03:45:19 GMT)
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It occurs that this might be translated as "hosted Communication Provider/Reseller", but I would still insert "Communication" due to the particular voice telephony nature of the discussion.

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Note added at 9 days (2010-10-20 17:04:29 GMT) Post-grading
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It sounds to me like your client has more or less (unilaterally?) "backported" the idea of "hosted" from the data/web area into the telephony area; when I worked in that area we never used that term.

Given the current environment and your client's specific terminology I would probably go with your choice as well.