The ratings of three Diversified Telecommunication Services stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Elephant Talk Communications Corp.‘s (AMEX:ETAK) rating falls this week to a F (“strong sell”), down from last week’s D (“sell”). Elephant Talk Communications provides voice, data transmission, pre-paid calling cards, and Internet service provider services. In Portfolio Grader’s specific subcategories of Earnings Momentum, Equity, Cash Flow, and Sales Growth, ETAK also gets F’s. For a full analysis of ETAK stock, visit Portfolio Grader.

France Telecom‘s (NYSE:FTE) rating weakens this week, dropping to a F versus last week’s D. France Telecom provides telecommunications services to residential, professional, and large business customers. The stock gets F’s in Earnings Surprise and Sales Growth. The stock price has dropped 6.4% over the past month, worse than the 1% decrease the S&P 500 has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of FTE stock.

This week, ORBCOMM Inc. (NASDAQ:ORBC) falls to a D (“sell”), worse than last week’s grade of C (“hold”). ORBCOMM operates low earth orbit satellites and ground infrastructure that enable customers to track, monitor, control, and communicate with fixed and mobile assets located anywhere in the world. The stock also gets an F in Earnings Revisions. The stock price has fallen 10.9% over the past month. To get an in-depth look at ORBC, get Portfolio Grader’s complete analysis of ORBC stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.