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Our Windows based application dials out to multiple devices using RS-232 connections over RAS with a null modem connection.

These connections are created by calling RasSetEntryProperties with a dwType of RASET_Phone on Vista or 7 and RASET_Direct on previous versions of windows.

From our investigations Vista and Windows 7 can only maintain 5 concurrent RAS connections before dropping older connections when dialed and 9 on Windows XP and 2000.

Are these hard limits in Windows or could this be pointing to other issues in how we communicate of the sockets to these remote devices?

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