extra signaling needed in advanced service features, such as voice response systems and call management. Other manufacturers Beginning in the early 1950s, 500-style phones were also made under license by ITT Kellogg (now Cortelco), who continued manufacturing the original rotary design, marketed as the Cortelco ITT-500AS (desk phone) and Cortelco ITT-554AS (wall phone), until discontinuation on January 1, 2007. The design was also produced in Canada by Northern Electric, which eventually became Northern Telecom. Cortelco continues to produce a non-dial version of the model 500, known as the Model 89001047PAK; this phone is available only in bright red color. Stromberg-Carlson (now part of Siemens) also made the phones from the 1950s-1980s. Replicas Some contemporary replicas of the 500 model are available. While faithful from a cosmetic point of view, they are internally very different from the original, including a rotating tone dialer based on optical technology. In popular culture The Model 500 series, and its distinctive ring, are near-ubiquitous in late 20th-century U.S. and Canadian film and television. Model 500s are featured as a weapon in the movie True Lies. Touch-tone successors Model 1500 The Western Electric model 1500 telephone adapted the 500 design for touch-tone dialing with a push-button pad for the digits 0 through 9. It was produced from 1963 to 1968. In addition to the basic single-line model 1500D, the 1500-series included many related variations and special purpose models with additional features. This included sets with a headset jack, 2-line sets (1510F), key sets (1560), call directors, panel phones (1750), industrial phones (1520), and automatic dialers (1660). Model 2500 By the late 1960s, interactive response systems in some industries required additional signaling beyond the ten digits. In 1968, the push-button dial pad was extended with two additional keys, the # (pound) and * (asterisk), which marked the introduction of the 2500-type telephone. The additional keys were located on either side of the 0 button to fill the matrix of 4-by-3 keys. These keys were initially unused by most customers but would later be used for vertical service codes and voice mail menu navigation. In 1974, when modular connectors were introduced, the 2500 telephone was fitted with modular connectors on handset and line cords, resulting in type designations suffixed with M, e.g., 2500DM. The 2500 is still commonly encountered and it is still produced by several companies. In addition to the basic single-line model, the Western Electric 2500-series