CASA Casa Systems Inc

FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES                                                                                   
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940                       

1. Name and Address of Reporting Person * Xie Lucy	2. Issuer Name and Ticker or Trading Symbol Casa Systems Inc [ CASA ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director                    _____ 10% Owner __X__ Officer (give title below)    _____ Other (specify below) SVP of Operations
(Last)          (First)          (Middle) C/O CASA SYSTEMS, INC., 100 OLD RIVER ROAD	3. Date of Earliest Transaction (MM/DD/YYYY) 3/2/2021
(Street) ANDOVER, MA 01810 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	3/2/2021		M		39977	A	(1)	2167710	D
Common Stock	3/2/2021		F(2)		17749	D	$8.02	2149961 (3)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(4)	3/2/2021		M			39977	(5)	(5)	Common Stock	39977	$0.00	39977	D

Explanation of Responses:
(1)	Restricted stock units ("RSUs") converted into common stock, $0.001 par value per share (the "Common Stock"), of Casa Systems, Inc. (the "Company") on a one-for-one basis upon vesting of the units.
(2)	Shares withheld by the Company to satisfy tax withholding requirements on vesting of RSUs. No shares were sold.
(3)	Due to a scriveners error, on February 25, 2021, the reporting person filed a Form 4 that inadvertently overstated the number of shares held by the reporting person by 810 shares. This Form 4 corrects such error by reducing the number of shares held by the reporting person by such 810 shares.
(4)	Each RSU represents the right to receive one share of Common Stock upon vesting, subject to the reporting person's continued service relationship with the Company and the other terms and conditions set forth in the applicable RSU agreement. In the sole discretion of the Company's board of directors, the Company may, with respect to any applicable vesting date, deliver to the reporting person Common Stock or cash having a fair market value equal to the number of shares of Common Stock underlying the portion of the RSU that vested on such date, payable within 30 days of the vesting date, less applicable taxes.
(5)	These RSUs are scheduled to vest based upon the Company's level of achievement of pre-established performance parameters, as approved by the Company's Board of Directors, related to either or both of (i) the Company's relative Total Shareholder Return ("TSR") performance against the TSR of the companies listed in the Russell 2000 Index, and (ii) the absolute stock price performance of the Company's common stock, in each case, measured over the three-year period beginning on February 25, 2020 and ending on February 25, 2023, and subject to the other terms and conditions set forth in the applicable RSU agreement. The RSUs have no expiration date.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Xie Lucy C/O CASA SYSTEMS, INC. 100 OLD RIVER ROAD ANDOVER, MA 01810	X		SVP of Operations

Signatures
/s/ Timothy Rodenberger, as Attorney-in-Fact		3/4/2021
**Signature of Reporting Person		Date