<PAGE>
                                                                   Exhibit 10.24

                        [Letterhead of Kevin Pennington]


February 28, 2001

Mr. Ronald D. Black
Mas Hadrien
Route Du Plan Du Lorgue
Saint Marc Jaumegarde
13100 Aix En Provence
France

Dear Ron:

It gives me great pleasure to offer you an Officer position with Agere Systems
Inc., formerly known as the Microelectronics Group of Lucent Technologies Inc.
(hereinafter "Agere" or the "Company"). In addition to confirming my offer,
this letter sets out the terms and conditions of your employment. It also
outlines the current major features of Agere's compensation and benefit plans
and practices.

As you are aware, Lucent has announced its intention to spin-off Agere into a
separate company initially through an IPO, which is expected to occur in the
first quarter of calendar 2001, with the actual spin-off currently scheduled
for later in calendar 2001. All of the plans referred to in this letter reflect
the current compensation and benefit plans that apply to Lucent employees. It
is expected that Agere will initially adopt most of these plans, although many
of the decisions associated with compensation and employee benefit design
post-spin have not been finalized, and it is expected that changes will occur
from the current offerings.

ASSUMPTION OF DUTIES: We propose that effective on or about March 15, 2001, you
will assume the position of Senior Vice President--Corporate Strategy and
Development of Agere Systems reporting to the President and Chief Executive
Officer. Your work location will be in the headquarters of Agere in Allentown,
Pennsylvania.

COMPENSATION COMPONENTS: The Company's fiscal year begins October 1 and ends
September 30. Currently, compensation consists of three components: Base
Salary, a Short Term Incentive Award, and Stock Option grants made under the
Long Term Incentive Program. These components are described below.

BASE SALARY: Your initial annual base salary will be $350,000. Employees are
paid monthly and based on a March 15, 2001 date of hire, you would receive your
first paycheck at the end of April and thereafter at the end of each month.

SHORT TERM INCENTIVE AWARD: Your target bonus opportunity is 65% of your base
salary (i.e., 65% x $350,000 = $227,500). Above target performance would, of
course, yield above target compensation, consistent with Agere's
pay-for-performance philosophy. For the 2001 fiscal year, you will receive a
guaranteed minimum award of 100% of target bonus if your start date is March
15, 2001. This award will be payable in the same form and timing as awards
granted to other Agere officers.

STOCK OPTIONS: As an officer of Agere, you will be eligible to receive
non-qualified stock option

<PAGE>
Ronald B. Black
February 28, 2001
Page 2


grants under the Long Term Incentive Program ("LTIP"). The plan provides for
supervisory assessment of your performance in awarding options. As with the
Short Term Incentive, Long Term Incentives are closely linked to performance
and with the Company's strategy to meet the challenges of an ever-changing
marketplace. The Company cannot guarantee continuation of the LTIP in its
current format, nor can it guarantee annual grant levels to individual
participants. At the IPO, Agere will adopt its own Long Term Incentive Plan and
it is currently expected that all stock option grants to you will be made from
that plan.

HIRING INCENTIVE: In order to encourage you to join Agere and address your
incentive forfeitures, the Company will provide you with the following:

--  We will ask the Stock Awards Committee to award you a stock option grant of
    400,000 Agere stock options at the IPO. The term of the option will be seven
    years with vesting over a four year period from the date of the grant as
    follows: 25% vests one year after the grant date and the remaining options
    vest monthly in equal amounts over the next 36 months. The option price will
    be the price offered to all other employees receiving the IPO grant, yet to
    be determined. The specific terms of your stock options will be contained in
    the Agere Long Term Incentive Plan document and in your individual Stock
    Option Agreement. You will receive your Agreement after the Committee
    approves your grant at the time of the IPO.

--  We will ask the Agere Stock Awards Committee to approve a hiring grant of
    25,000 Agere Restricted Stock Units, which will be granted at the IPO.
    Vesting will be 1 year cliff vesting from the date of hire.

--  The Company will provide you with a cash sign-on bonus of $200,000, less
    applicable taxes, payable within 30 days of your hire date. Such payments
    will not be made if you voluntarily resign your position with Agere prior to
    the time the payments are due.

Amounts paid under this hiring incentive section are not considered earnings
for employee benefit purposes.

SEVERANCE BENEFIT: In the event of any Company initiated termination other than
for "cause" (as defined below) under the Company's officer severance policy you
will be entitled to a severance payment equal to two times your base salary and
target incentive in effect at the time of termination.

In addition, if the spin-off does not occur by March 1, 2002, and the Company
does not offer you continued employment as an officer at least at the same
salary and target incentive level, and in the central New Jersey/eastern
Pennsylvania area, you would be eligible to receive the severance benefit
described above.

Such severance payment as described above, will be conditioned upon you signing
a release and agreement not to sue the Company or any affiliate of the Company.
The form of this release and agreement will be the same as the standard release
then in use for Company officers.

For purposes of this employment letter, "cause" shall be defined as follows:
(1) your conviction (including a plea of guilty or nolo contendere) of a felony
or any crime of theft, dishonesty or moral turpitude; or (2) gross omission or
gross dereliction of any statutory or common law duty

<PAGE>
Ronald B. Black
February 28, 2001
Page 3

of loyalty to the Company, or (3) violation of Lucent's Business Guideposts --
the Company's Code of Conduct (or successor document).

SPECIAL PAYMENT: In order to address the unlikely possibility that the spin-off
does not occur prior to March 1, 2002, which could diminish the scope of your
responsibilities as SVP Corporate Strategy and Development, you would be
eligible to receive a cash payment of $577,500 (less applicable taxes) on
March 1, 2002, if, by that time, you remain employed with Lucent Technologies.

OFFICER AND GENERAL EMPLOYEE BENEFITS PLANS: Attachment A is a summary of
benefits available to you under the current officer and general employee benefit
plans. A Benefits representative will personally meet with you to review these
benefit plans.

RELOCATION PLAN: You will be eligible for the standard relocation package.
However, before we can commit to specifics we will need more details concerning
your current situation in France.

Should you voluntarily resign from your position at Agere (or subsequent
position with Lucent Technologies in the event the spin-off does not occur)
within 24 months of your employment date, you agree to reimburse the Company for
all costs associated with your relocation.

CONFIDENTIALITY OF AGREEMENT: It is agreed and understood that you will not talk
about, write about or otherwise disclose the terms or existence of this
employment letter or any fact concerning its negotiation or implementation. You
may, however, discuss the contents of this letter with your family, legal and/or
financial counselor.

CONTINGENCY OF OFFER: This offer of employment is contingent upon the successful
completion of reference checks and upon your meeting our medical requirements.
Our medical review includes an evaluation of your Preplacement Health
Questionnaire, a mandatory drug screen, and a physical examination. A positive
drug screen result will automatically mean rescission of this employment offer.

This letter supersedes and completely replaces any prior oral or written
communication about your employment with Agere. This letter is not an employment
contract and should not be construed or interpreted as containing any guarantee
of continued employment. The employment relationship at the Company is by mutual
consent ("Employment-At-Will"). This means that managers have the right to
terminate their employment at any time and for any reason. Likewise, the Company
reserves the right to discontinue your employment with or without cause at any
time and for any reason.

BENEFIT PLAN TERMS: The incentive plans as well as the employee and officer
benefit plans, programs and practices as briefly outlined in this letter,
reflect their current provisions. Payments and benefits under these plans and
programs, as well as other payments referred to in this letter, are subject to
IRS rules and regulations with respect to withholding, reporting, and taxation,
and will not be grossed-up unless specifically stated. The Company reserves the
right to discontinue or modify any compensation, incentive, benefit, perquisite
plan, program or practice. Moreover, the very brief summaries contained herein
are subject to the terms of such plans, programs and practices. If there is any
difference between these summaries and the formal plan documents, the provisions
of the plan documents will prevail.

For purposes of the officer and employee benefits plans, the definition of
compensation is as stated in the plans. Currently, pensions are based on base
salary and actual short term
<PAGE>
Ronald B. Black
February 28, 2001
Page 4

incentive awards. Other pay-related benefits are based either on base salary
or base salary plus the target award under the short term plan. All other
compensation and payments reflected in this offer are not included in the
calculation of any employee or officer benefits (except for the Deferred
Compensation Plan which currently permits the deferral of base salary and
certain incentives).

NON-COMPETITION: The Supplemental Pension Plan, the Deferred Compensation Plan
and the Executive Life Insurance Plan are subject to non-competition
constraints.

PROPRIETARY INFORMATION AND EMPLOYMENT LIMITATIONS: By acceptance of this offer,
you agree that (1) no trade secret or proprietary information belonging to your
previous employer will be disclosed or used by you at the Company, and that no
such information, whether in the form of documents, memoranda, software,
drawings, etc. will be retained by you or brought with you to the Company, and
(2) you have brought to the Company's attention and provided it with a copy of
any agreement which may impact your future employment at the Company, including
non-disclosure, non-competition, invention assignment agreements or agreements
containing future work restrictions, and that you certify that you have no
restrictions under any agreement of this type that would impact this work
assignment at Agere.

If you agree with the foregoing, and affirm that there are no agreements or
other impediments that would prevent you from providing exclusive service to the
Company, please sign this letter in the space provided below and mail the
original executed copy to me at your earliest convenience.

Ron, we would be very pleased to have you join the team and are excited about
the opportunity we would have to achieve breakthrough results together at Agere.
As a Company, we have never been better positioned to take full advantage of the
opportunities for growth and success in our marketplace. I look forward to
having you join us. If you have any questions, please do not hesitate to call
me, Tom O'Hara, Vice President, Compensation and Benefits on (510) 712-5512 or
Rebecca Bishee of our Executive Compensation and Benefits group on (908)
582-1102.

Addendums:

        . Tax preparation for 2000 and 2001
        . Relocation in summer after school ends.

I look forward to your response.

Sincerely,



/s/ Kevin Pennington
Kevin Pennington
SVP Human Resources
Agere Systems Inc.

/s/ Ronald D. Black           14 Mar 01
Acknowledged and Agreed to:   Date
Ronald D. Black


Attachments(1)