Question: What are the call letters of the sports radio station, also known as "The Fan" that broadcasts from the same building as sister station WNNX, a mainstream rock station?
Context: WSID was a radio station that served the substantial African-American community in Baltimore, Maryland.  It advertised itself as "Baltimore's #1 black station".  It was founded by Sidney Tinsley (thus the call letters) as an AM station in 1947; a new owner in 1949 changed format to cater to African-American listeners.  Its frequency was originally 1570, but to increase its signal strength (the power permitted by the FCC being different on different frequencies) it moved in the 1950s to 1010.  In the 1960s, sister station WSID-FM signed on the air on 92.3, simulcasting WSID-AM.  Pauline Wells Lewis hosted a gospel music program, which constituted its morning programming six days a week.  In the afternoon and evening it programmed R&B, including a lot of Motown music, then in its heyday.  Afternoon host was Fat Daddy (Paul Johnson).  In 1968, the FM station abandoned the black programming and changed its call letters to WLPL-FM, but the AM station continued the black programming until 1983.  The AM frequency is currently used by WOLB, but it has no connection with WSID other than the frequency. WJKD (99.7 FM) is a radio station broadcasting a Jack FM format.  Licensed to Vero Beach, Florida, USA, the station is currently licensed to Vero Beach Broadcasters, LLC.  99.7 went on the air on March 27, 1992, as WWDO FM.  From 1995-2001, the station consisted of a country music format, and branded itself as "Panther Country 99.7," with the call letters, WPAW.  On March 5, 2001, the station changed to an 1980s hits format.  It rebranded itself as "99.7 GNX," to reflect the new call letters WGNX, and its slogan ""The music of Generation X"."  In 2003, WGNX added a few hits from the 1970s and 1990s to its playlist, making it more like a variety station, although its music format continued to be, for the most part, the same.  In 2004, WGNX tried a daring move by starting up a new radio show that featured alternative rock music on Saturday nights.  However, the idea did not go over well, and the station cancelled the show.  In December, 2006, WGNX rebranded itself as "997 Jack FM," and changed its call letters to WJKD.  Jack FM's playlist features hit music across multiple genres (mostly pop and rock) from the 1960s to present-day.  Their slogan, "Playing What We Want," promotes Jack FM as having a larger playlist with more variety than most commercial radio stations, thus giving the station a reason not to take requests from its listeners. KVKI-FM (96.5 FM) is a radio station broadcasting an adult contemporary music format.  Licensed to Shreveport, Louisiana, United States, the station serves the Shreveport area.  The station is currently owned by Townsquare Media.  Its studios are shared with its other five sister stations in West Shreveport (one mile west of Shreveport Regional Airport), and the transmitter is in Blanchard, Louisiana.  The call letters were originally KBCL, and later became religious station KEPT, before the call letters were changed to KVKI to be similar to the call letters of the popular KVIL radio station in Dallas, Texas. WAKY (620 kHz AM) is a classic hits radio station in the Louisville, Kentucky metropolitan area.  It is currently owned by William Walters, through licensee W & B Broadcasting Co., Inc.  The station used to share a significant portion of Spanish programming with sister station WTUV-FM (105.7 FM) until WTUV-FM was sold to UB Louisville and became English-language sports radio station WHBE-FM.  The original station call letters, under different owners, were WTMT (1958–2010). WNNX (100.5 FM, "Rock 100.5") is an Atlanta radio station airing a Mainstream Rock format.  It is owned and operated by Cumulus Media.  The station broadcasts from the same building as its other Cumulus Atlanta sister stations WWWQ ("Q100"), W255CJ 98.9 "99X", W250BC 97.9 "OG 97-9", WKHX 101.5 "Kicks 101-5", WYAY FM 106.7 "NewsRadio 106.7", and Dickey Broadcasting's WCNN "680 The Fan" and W229AG 93.7 in Sandy Springs near the Georgia Highway 400 and Interstate 285 interchange.  WNNX's main transmitter is located in downtown Atlanta atop the Westin Peachtree Plaza Hotel. WRXR-FM (105.5 FM) is a commercial radio station licensed to Rossville, Georgia, USA, broadcasting to the Chattanooga, Tennessee, area.  WRXR broadcasts a mainstream rock music format branded as "Rock 105".  WRXR was the second station in Chattanooga to start broadcasting in HD radio.  Previously the call letters were used for a classic rock station in Chicago.  That station became smooth jazz WNUA. The Mountain, is an adult album alternative radio station in Pittston, Pennsylvania.  The station's website states "Independent Radio" as part of its mission.  Station IDs often include the phrase "It's different here."  On August 5, 2013 The Mountain moved from its original frequency at 102.3 MHz under the call letters of WDMT to 98.5 MHz on the HD2 band and assumed the call letters WKRZ-HD2 from its sister station 98.5 KRZ.  The Mountain and 98.5 KRZ are owned and operated by Entercom Communications including radio stations WKRZ, WGGY, WILK-FM, WILK and most recently WHBS, taking The Mountain's frequency at 102.3 MHz under a new format. KLIK (1240 AM), branding as Newstalk 1240, is a radio station broadcasting a News Talk Information format.  Licensed to Jefferson City, Missouri, United States, the station serves the Columbia, Missouri area.  The station is currently owned by Cumulus Media and features programing from ABC Radio and Westwood One.  KLIK also operates a local news operation with sister station KFRU (1400 AM in Columbia, Missouri).  From 1954 until September 8, 1999, KLIK was located at 950 AM, transmitting with a daytime power of 5000 watts and a nighttime power of 500 watts (directional) from a four tower array about 3.2 miles south of Jefferson City.  Early owners of KLIK broadcast a varied format of news and talk programs including music programs of middle of the road, top 40, adult contemporary and country music as 95 KLIK.  For many years, KLIK and KJFF as the two largest regional radio stations (the most powerful AM and FM station in the region) dominated radio listenership in cumulative market share in the Columbia-Jeff City Market of Central Missouri.  In the 1970s and early 1980s KLIK was known as the Live 95 as its broadcasts were all programmed by live deejays, talk hosts and newscasters rather than by a satellite or automation system.  KLIK once operated with an FM sister station in the 1970s and 1980s known was KJFF 106.9 FM a 100,000 watt semi-automated easy listening music station with a large regional coverage signal.  In the early 1980s KLIK and KJFF-FM together were sold by the local Jefferson City operators to a regional group broadcaster, and newspaper publisher, Brill Media.  In about 1982, KJFF-FM 106.9 FM became an adult contemporary music station, initially with a satellite delivered music format, and easy listening music was phased out along with the KJFF call letters which were replaced by the new FM call signs of KTXY.  KLIK 950 AM transitioned over from AC/Contemporary music at about the same time to a 24-hour-a-day live country/western format known as 95 Country.  KLIK carried a variety of programming and a mostly country music format until the late 1990s. WCNN is an AM station broadcasting on a frequency of 680 kHz and serving the Atlanta-area radio market with a sports radio format.  The station is commonly known by the on-air branding as "The Fan".  The station formerly broadcast the audio portion of the CNN Headline News channel (hence its current callsign) along with some local news and commercials, a news radio format that the station pioneered in the 1980s and re-appeared on the station later in the station's history.  WCNN broadcasts with a power of 50,000 watts during the daytime, and 10,000 watts during nighttime, and is actually licensed to serve North Atlanta, with transmitter and towers located near Norcross, Georgia (in the northeastern Atlanta suburbs). WNNJ is a Class B1 FM radio station licensed to Newton, New Jersey broadcasting on 103.7 FM.  They serve the Sussex County, New Jersey radio market while also reaching northeastern Pennsylvania and Orange County, New York.  The station is owned by iHeartMedia, Inc..  WNNJ offers a classic rock format focusing on 1970s, '80s and '90s rock.  They also mix in some 1960s and current rock as well.  The station is known as "103-7 WNNJ The Tri States' Rock Station".  The station achieves high ratings as well.  The legal call letters of this station were WNNJ-FM from the Summer of 1988 until June 30, 2008.  The FM was dropped that day because their AM sister station on 1360 changed its call letters from WNNJ (which they had since 1953) to WTOC.
Answer: WCNN