time-sharing access, File Transfer Protocol (FTP) and rudimentary electronic mail protocols were developed and eventually ported to run over the TCP/IP protocol suite or replaced in the case of email by the Simple Mail Transfer Protocol. TCP/IP Steve Crocker formed a "Networking Working Group" in 1969 with Vint Cerf, who also joined an International Networking Working Group in 1972. These groups considered how to interconnect packet switching networks with different specifications, that is, internetworking. Stephen J. Lukasik directed DARPA to focus on internetworking research in the early 1970s. Research led by Bob Kahn at DARPA and Vint Cerf at Stanford University and later DARPA resulted in the formulation of the Transmission Control Program, which incorporated concepts from the French CYCLADES project directed by Louis Pouzin. Its specification was written by Cerf with Yogen Dalal and Carl Sunshine in December 1974 (). The following year, testing began through concurrent implementations at Stanford, BBN and University College London. At first a monolithic design, the software was redesigned as a modular protocol stack in version 3 in 1978. Version 4 was installed in the ARPANET for production use in January 1983, replacing NCP. The development of the complete Internet protocol suite by 1989, as outlined in and , and partnerships with the telecommunication and computer industry laid the foundation for the adoption of TCP/IP as a comprehensive protocol suite as the core component of the emerging Internet. Network applications NCP provided a standard set of network services that could be shared by several applications running on a single host computer. This led to the evolution of application protocols that operated, more or less, independently of the underlying network service, and permitted independent advances in the underlying protocols. Telnet was developed in 1969 beginning with RFC 15, extended in RFC 855. The original specification for the File Transfer Protocol was written by Abhay Bhushan and published as on 16 April 1971. By 1973, the File Transfer Protocol (FTP) specification had been defined () and implemented, enabling file transfers over the ARPANET. In 1971, Ray Tomlinson, of BBN sent the first network e-mail (, ). Within a few years, e-mail came to represent a very large part of the overall ARPANET traffic. The Network Voice Protocol (NVP) specifications were defined in 1977 (), and implemented. But, because of technical shortcomings, conference calls over the ARPANET never worked well; the contemporary Voice over Internet Protocol (packet