The "Telecom" refers to the fact that it was originally developed to support the software on Ericsson's telecommunications switches. So yes, for all you know, if you make a phone call, an Erlang-based switch may have routed your call.
"Open telecom platform" is powerful set of erlang libraries which allow you to create fault tolerant systems easily. It's not an OS or device. It's something which runs anywhere erlang runs.
