I think the information here below is very important. Why? Because you can make some conclusions out of it. One of the conclusions is that they have to get more revenues outside Europe. Another conclusion would be they are depending to much on two customers. These are risks that have to be considered before making an investment. 

Source: 10K - F12/F13  

At December 31, 2009, the Company had 92 telecom carriers, resellers, distributors and general corporate customers compared to 70 such customers at December 31, 2008.  For the years ended December 31, 2009 and 2008, resellers and distributors represented approximately 49% and 56% of the Company’s revenues, respectively.  

For the year ended December 31, 2009, 97% of total revenues were generated from forty-five European companies (of which one customer accounted for approximately 48%, and one customer accounted for approximately 22% of total revenues), and 3% from twenty-eight U.S., Asian, Australian and South American companies. For the year ended December 31, 2008, 83% of total Company’s revenues were generated from thirty-nine European companies and 17% from twenty-five U.S. and Asian companies.  

At December 31, 2009, trade receivables were due from 54 customers. Of these, three customers accounted for approximately 47%, 27% and 15% of the trade receivables, respectively.   At December 31, 2009, 19% and 45% of trade receivables were aged within 30 days and 120 days, respectively.  At December 31, 2009, the average age of trade receivables from all customers was 128 days as compared to 83 days at December 31, 2008. The average age of receivables from the Company’s four largest customers at December 31, 2009, was 138 days.