COMCAST CORPORATION

NEWS RELEASE

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Adele Ambrose, AT&T                          John R. Alchin, Comcast
Vice President Public Relations              Senior Vice President and Treasurer
908-221-6900 (office)                        (215) 981-7503
888-602-5420 (pager)

                                             William E. Dordelman, Comcast
Eileen M. Connolly, AT&T                     Vice President, Finance
Director Financial Communications            (215) 981-7550
908-221-6731 (office)
888-602-5417 (pager)                         Marlene S. Dooner, Comcast
                                             Senior Director, Investor Relations
                                             (215) 981-7392


                  AT&T and Comcast Agree To Swap Cable Systems
                    Comcast to Add 2 Million New Subscribers
            Two Companies To Collaborate In Offering Cable Telephony

FOR RELEASE:  TUESDAY, MAY 4, 1999

NEW YORK -- AT&T and Comcast  Corporation  today announced that they had reached
an agreement under which Comcast will be able to increase its cable  subscribers
by about two  million  households  and the two  companies  will  collaborate  in
bringing competitive local telephone service to Comcast's customers.

Under the  agreement,  AT&T and Comcast will  exchange  various  cable  systems,
resulting in a net addition to Comcast of approximately 750,000 subscribers. The
swaps are  designed  to improve  each  company's  geographic  coverage by better
clustering its systems. Because Comcast will receive more subscribers than it is
contributing  in the  swaps,  it will pay AT&T  consideration  having a value of
approximately  $4,500  per added  subscriber  for a total  value of $3.0 to $3.5
billion.  The  majority  of the  exchanges  are  subject  to  completion  of the
AT&T/MediaOne merger, as well as to customary closing conditions.

Comcast will also  receive an option from AT&T to purchase,  over the next three
years,  additional  cable  systems  with a total of  approximately  1.25 million
subscribers. The exercise of this option is also contingent on the completion of
the AT&T/MediaOne  merger. The price for these additional systems is expected to
be  consideration  having a value of  approximately  $5.7  billion  (subject  to
reduction for any long-term debt and other liabilities of the acquired systems).

                                    --more--

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Comcast has also agreed to offer AT&T-branded telephony in all of its markets on
an expedited basis, as soon as AT&T has concluded separate telephony  agreements
with at least two other non-AT&T affiliated  multiple system operators.  Comcast
will be entitled to the most favorable  terms AT&T has reached with any of those
cable operators.

"These  agreements are great news for millions of American families who will now
have a choice in local phone  service,"  said AT&T  Chairman  and CEO C. Michael
Armstrong.   "This   transaction  makes  strategic  sense  for  both  companies.
Geographic clustering enables more effective telephony competition.  And AT&T is
proud to join with Comcast in bringing AT&T-branded  communications  services to
its customers."

"This is a terrific outcome for Comcast shareholders.  Through this transaction,
Comcast firmly  establishes  its leadership role in the industry by becoming the
third-largest cable company, with more than 8 million subscribers. While growing
significantly  in absolute  terms, we have  strengthened  our local and regional
presence through  additional  clustering,"  said Brian L. Roberts,  President of
Comcast Corporation. "In addition to these valuable cable assets, this agreement
greatly  accelerates  our  entrance  into  telephony  and will enable us to more
quickly create and provide  important new products to our  customers.  This is a
different  outcome  than our  MediaOne  proposal,  but it is an elegant  win-win
result."

The purchase  price for the net additional  subscribers  resulting from the swap
transactions can be paid in a number of ways, including in shares of AT&T common
stock currently owned or subsequently acquired by Comcast. The value of any AT&T
common  stock  exchanged  in these  transactions  will be set at  their  average
trading price during the  20-trading  day period  beginning June 6. When Comcast
exercises  its option to  acquire  the  additional  systems  serving  AT&T cable
subscribers, it will compensate AT&T in shares of Comcast Class A Special Common
Stock  (CMCSK),  which will be valued on the same basis,  or with other forms of
consideration of equivalent value.

Except for any portion of the swap transactions paid in cash or in certain other
equity  securities,  each of these transactions is expected to be concluded on a
tax-free basis.

AT&T was advised by Goldman,  Sachs & Co., CS First  Boston and  received  legal
counsel  from  Wachtell,  Lipton,  Rosen & Katz.  Comcast was advised by Salomon
Smith Barney, Lazard Freres & Co. LLC., and Davis Polk & Wardwell.

AT&T  (http://www.ADT.com)  is the  world's  premier  provider of voice and data
communications,  with  more than 80  million  customers,  including  businesses,
government  and  consumers.   AT&T  runs  the  world's  largest,  most  powerful
long-distance  network and the largest  wireless  network in North America.  The
company is a leading  supplier of data and Internet  services for businesses and
the nation's largest direct Internet  service  provider to consumers.  AT&T also
provides local telephone service to a growing number of businesses.

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Comcast  Corporation  (http://www.comcast.com)  is  principally  engaged  in the
development,  management  and operation of broadband  cable  networks and in the
provision of content through principal ownership of QVC,  Comcast-Spectacor  and
Comcast SportsNet,  a controlling  interest in E!  Entertainment  Television and
through programming investments.

Comcast's  Class A Special  Common  Stock and Class A Common Stock are traded on
The Nasdaq Stock Market under the symbols CMCSK and CMCSA, respectively.






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