MarshallSoft DUN Dialer for C/C++ - Version 2.1 MarshallSoft DUN Dialer for C/C++. Ver 2.1.(MDD4C21.ZIP) 06/07/2002. Use 32-bit WindowsDialup Networking (DUN) to dial up anyinstalled Internet Service Provider (ISP).Requires a 32-bit Windows C/C++ compiler. See http://www.marshallsoft.com/mdd4c.htm. Registration is $55 (for email delivery) or $40 for currently registered users of any MarshallSoft winsock product.