EXHIBIT 5.1     
 
[SWIDLER & BERLIN LETTERHEAD]
 
                               January 23, 1997
 
The Board of Directors
Telegroup, Inc.
2098 Nutmeg Avenue
Fairfield, Iowa 52556
 
  Re: Registration Statement on Form S-4
 
Gentlemen:
 
  We have acted as counsel to Telegroup, Inc., an Iowa corporation (the
"Company"), with respect to the Company's Registration Statement on Form S-4
(the "Registration Statement") filed with the Securities and Exchange
Commission, in connection with the registration under the Securities Act of
1933, as amended (the "Securities Act"), of $97,000,000 aggregate amount
outstanding at maturity of 10 1/2% Senior Discount Notes due 2004 (the
"Notes"). This opinion letter is furnished to you at your request to enable
you to fulfill the requirements of Item 601(b)(5) of Regulation S-K, 17 C.F.R.
ss. 229.601(b)(5), in connection with the Registration Statement.
 
  As counsel to the Company, we have examined the Company's Articles of
Incorporation, as amended (the "Articles"), and such Company records,
certificates and other documents and relevant statutes, regulations, published
rulings and such questions of law as we considered necessary or appropriate
for the purpose of this opinion.
 
  In our examination, we have assumed the authenticity of original documents,
the accuracy of copies and the genuineness of signatures. We have relied upon
the representations and statements of officers and other representatives of
the Company with respect to the factual determinations underlying the legal
conclusions set forth herein. We have not attempted to verify independently
such representations and statements.
 
  This opinion letter is based as to matters of law arising solely under the
laws of the State of New York as currently in effect, and we express no
opinion herein as to any other laws, statutes, ordinances, rules or
regulations.
 
  Based upon, subject to and limited by the foregoing and the other
qualifications herein, we are of the opinion that, when the Registration
Statement has become effective under the Securities Act, and upon issuance and
delivery of such Notes as contemplated by the Registration Statement, such
Notes will be binding obligations of the Company.
 
  We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to all references to our firm in the Registration
Statement. In giving this consent, we do not admit that we come within the
category of persons whose consent is required under Section 7 of the
Securities Act or the rules promulgated thereunder.
 
  This opinion is rendered solely for your benefit in connection with the
transactions described above upon the understanding that we are not hereby
assuming any professional responsibility to any other person. Except as
provided in the preceding paragraph, this opinion may not be relied upon by
any other person and this opinion may not be used, disclosed, quoted, filed
with a governmental agency or otherwise referred to without our express prior
written consent. The opinions expressed in this letter are limited to the
matters expressly set forth herein, and no other opinions should be inferred
beyond the matters expressly stated herein.
 
                                          Very truly yours,
 
                                          Swidler & Berlin, Chartered