UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of

the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): April 4, 2013

NEUTRAL TANDEM, INC.

(Exact name of registrant as specified in its charter)

550 West Adams Street

9th Floor

Chicago, Illinois 60661

(Address of principal executive offices, including Zip Code)

(312) 384-8000

(Registrant’s telephone number, including area code)

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On April 4, 2013, the Board of Directors (the “Board”) of Neutral Tandem, Inc. d/b/a Inteliquent (the “Company”) voted to increase the size of the Board from six to seven members and to appoint Joseph A. Beatty as a new director to fill the vacancy created by such increase, effective immediately.

Mr. Beatty has served as President and Chief Executive Officer of Telular Corporation (NASDAQ: WRLS) since 2008. Mr. Beatty also serves as a member of the board of directors of Telular Corporation. Mr. Beatty intends to step down from his responsibilities with Telular Corporation on May 2, 2013. Prior to serving as its President and Chief Executive Officer, Mr. Beatty served as Telular Corporation’s Executive Vice President (beginning in April 2007) and Chief Financial Officer and Secretary (beginning in May 2007). From June 2003 until June 2006, Mr. Beatty was President and Chief Executive Officer of Concourse Communications Group, a privately held developer and operator of distributed antenna systems and airport wi-fi networks. In June 2006, Concourse was sold to Boingo Wireless. From March 2001 until June 2003, Mr. Beatty worked with private equity firm Cardinal Growth L.P. on various acquisition projects and also acted as part-time Interim Chief Financial Officer for Novaxess B.V., a privately held telecom services provider based in the Netherlands. From November 1996 until February 2001, Mr. Beatty was a co-founder and the Chief Financial Officer of Focal Communications Corporation, a publicly held telecom services provider. Earlier in his career, Mr. Beatty was a securities analyst and also held numerous technical management positions for a local telecom services provider. Mr. Beatty is a former Chairman and continues to serve on the board of trustees of Edward Health Services Corporation, a not-for-profit healthcare provider located in Naperville, Illinois. He is also a director of EHSC Cayman Segregated Portfolio, its captive insurance subsidiary, domiciled in the Cayman Islands. Mr. Beatty earned a bachelor’s degree in electrical engineering from the University of Illinois and an MBA from the University of Chicago’s Booth School of Business. He is also a Chartered Financial Analyst.

In connection with his appointment, Mr. Beatty will receive an annual retainer of $150,000, paid quarterly in advance in the form of cash or restricted stock as determined by the Company.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.