As expected, Netscape Communications Corp yesterday tried to apply the brakes to Microsoft’s seemingly inevitable railroading of the internet browser market by signing up five regional Bell operating companies (RBOCS) to use Navigator, and its Communicator successor, as their default browser. The five are Pacific Bell, Southwestern Bell, Ameritech, Bell Atlantic and BellSouth, which supposedly cover a potential market of some 72 million online users in 26 states between them, though nobody was willing to give any real subscriber details yesterday, apart from Bell South and Pacific Bell talking about tens of thousands of users, with the others mute. Through something called ISP Select, visitors to Netscape’s web site will be able to switch to one of the five ISPs by establishing an account on the spot. The RBOC’s servers will have a real-time link to Netscape’s servers. There will be other ISPs listed, but without the real-time links. There were no financial details revealed. ISP Select is aimed at business users using the web at work and selecting their home service while on-line at work. The group plans to be able to enable users to bill their net access through their regular phone bills some time in the future. Internet Explorer devotees will be able to stay with it; it’s a default rather than exclusive deal after all. The markets got very excited at what looked like the re-start of the browser wars, and pushed Netscape’s shares up $5 at one point, before closing up $3, or 5% at $63 yesterday.