OTC Markets Group provides level 2 quotes for OTCQX, OTCQB, and OTC Pink marketplaces, totaling 9,861 securities (as of March 4, 2015). If you are interested in accessing their level 2 quotes you can find a full list of OTC Markets Group's data distributors at the following link:
The chart on that page tells you all of the vendors' names, whether they offer level 1+ quotes, whether they offer level 2+ quotes, and how that data may be accessed—which usually involves subscribing through one of the vendors.
There may be other vendor's that provide OTC level 2 quotes, a Google search certainly yields more results, but given that OTC Markets Group does not provide many of those vendors on their list, it is uncertain whether those are true real-time level 2 quotes and/or whether those companies are at all reliable or trustworthy.
OTC Market Group is the originator of all the price and liquidity information for OTC marketplaces. If in doubt on any vendors who offer level 2 quotes for these OTC markets, OTC Market Group offers their own level 2 services which can be found at their webpage.