The agent for Net-phone company SunRocket, which folded suddenly this week leaving 200,000 subscribers in the lurch, has named the preferred companies that will provide VoIP service to SunRocket’s former customers. But experts say the scope of the transfer is unprecedented and could take weeks or even months.

    Management firm Sherwood Partners said Packet8 and Unified Communications will take on the former SunRocket subscribers, leaving those customers’ original phone numbers intact. But Palo Alto, California–based Sherwood offered no timetable for when this transfer, if it occurs, will be completed. The company did not respond to calls asking for information on how long a transfer of this magnitude could take.

    “Transferring tens of thousands of VoIP users from one service provider to another has not really been tried before as far as I know,” said Jack Rynes, president of Jaduka, a Dallas-based supplier of web-to-voice products for businesses.

    Offering consumer VoIP service involves organizing a set of individual relationships with ISPs and phone companies and developing and distributing a unique device that users attach to their computers. The device is usually tuned to the service provider, such as SunRocket or Vonage, so transferring a subscriber from one service to another involves sending customers a new connection device in the mail. Subscribers are identified by both their phone number and carrier, so the complex system of directories and devices that route phone calls has to be informed of any change.

    “If you try to switch a SunRocket subscriber over to Vonage, the network would not know about that transfer immediately,” said Mr. Rynes. “If this is all managed correctly, this could take several weeks. If not, it could take months.”

    Transferring subscribersfromone service to another in the traditional phone system takes far less time because the call routing system operates on a common standard, according to Mr. Rynes.