After winning approval from the Federal Communications Commission last week to purchase all the stock of Private Transatlantic Telecommunications Systems Inc and thus become a co-owner in a transatlantic cable venture with Cable & Wireless Plc of the UK, Nynex has now filed a request with the Department of Justice for similar approval. Nynex wants the Department of Justice to make a recommendation that the court should grant a waiver; a waiver is required for the regional Bell operating companies to provide such services, as established under the consent decree governing the Bell System breakup.