April 5, 1962 Oshkosh Northwestern
1962 brought direct distance dialing to Menasha and the advent of...area codes.
Initial use of area codes in the United States and Canada began in 1947 with large cities. Area codes were assigned based on the length of time a rotary dial phone took to dial the area code. Densely populated areas like New York City, Chicago, Los Angeles, and Detroit had huge incoming call volume and were assigned numbers (212, 312, 213, 313) that could be quickly dialed from a rotary dial phone. On a rotary dial phone low digits (1, 2, 3, 4) could dial quickly as the time the rotary dial took to return to the home position was minimal. High digit numbers (7, 8, 9, 0) on rotary dial phones took much longer to return to the home position and were usually used in less densely populated areas like rural Texas (915). This numbering strategy became unnecessary when touch-tone phones arrived, as the tone allowed instant entry of digits. Based on the above logic, with Milwaukee being the state's largest city, it made sense that it would be in the 414 area code while the more rural northern counties would be relegated to 715. Why Menasha and the rest of the Fox Valley was included in 414 was either because it was reflective of the growing population base from Fond du Lac to Green Bay or perhaps a convenience due to geography.
Of course, Menasha now finds itself in the 920 area code, created in 1997, and starting in 2014, I read that area code 274 has been proposed to join in the 920 area over much of eastern Wisconsin. Implementation was planned to begin in 2012, but conservation efforts and less need for numbers because of the economic crisis caused the date to be pushed back to 2014. Beginning then, all new telephone numbers will have the 274 area code, while old ones will keep their 920 area code.
That phone pictured below is definitely from a more simpler time.