SCHEDULE I

Exhibit 10.1

[Lifeline Systems, Inc. Logo]

September 13, 2004

Mr. Jeffrey W. Ubben and

    the other individuals and entities listed on Schedule I hereto

435 Pacific Ave.

4^th Floor

San Francisco, CA 94133

To Whom It May Concern:

Reference is hereby made to that certain Agreement, dated as of June 30, 2002 (the “Agreement”), among Lifeline Systems, Inc., a Massachusetts corporation (the “Company”), and (a) ValueAct Capital Partners, L.P., (b) ValueAct Capital Partners II, L.P., (c) ValueAct Capital International, Ltd., (d) VA Partners, L.L.C., (e) Jeffrey W. Ubben, (f) George F. Hamel, Jr. and (g) Peter H. Kamin (collectively and individually, “ValueAct”).

The Company and ValueAct agree that the term “Company” as defined and used in the Agreement is hereby modified to also include (1) all successors and assigns of Lifeline Systems, Inc. (a Massachusetts corporation in existence on the date hereof), whether by merger, share exchange, entity conversion or otherwise, and (2) any corporation or other entity that beneficially owns, either directly or indirectly, all of the outstanding capital stock, units or interests, as applicable, of Lifeline Systems, Inc. (a Massachusetts corporation in existence on the date hereof) or its successors or assigns. For the avoidance of doubt, the Company and ValueAct further agree that the term “Common Stock” as defined and used in the Agreement is hereby modified to also include the common stock of (1) all successors and assigns of Lifeline Systems, Inc. (a Massachusetts corporation in existence on the date hereof), whether by merger, share exchange, entity conversion or otherwise, and (2) any corporation or other entity that beneficially owns, either directly or indirectly, all of the outstanding capital stock, units or interests, as applicable, of Lifeline Systems, Inc. (a Massachusetts corporation in existence on the date hereof) or its successors or assigns.

Except as expressly set forth herein, nothing contained herein shall be deemed to alter or modify the terms and provisions of the Agreement. This letter agreement may be executed in counterparts, all of which together shall constitute one and the same instrument.

SCHEDULE I

ValueAct Capital Partners, L.P.

ValueAct Capital Partners II, L.P.

ValueAct Capital International, Ltd.

VA Partners, L.L.C.

Jeffrey W. Ubben

George F. Hamel, Jr.

Peter H. Kamin