Ownership Submission
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

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Triangle Private Holdings I, LLC
  2. Issuer Name and Ticker or Trading Symbol
PLANTRONICS INC /CA/ [PLT]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director __X__ 10% Owner
_____ Officer (give title below) __X__ Other (specify below)
See remarks
(Last)
(First)
(Middle)
C/O SIRIS CAPITAL GROUP, LLC, 601 LEXINGTON AVENUE, 59TH FLOOR
3. Date of Earliest Transaction (Month/Day/Year)
08/02/2018
(Street)

NEW YORK, NY 10022
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction 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 08/02/2018   A   2,904 (1) A $ 0 2,904 I See Footnotes (2) (3) (4) (5) (6) (7)
Common Stock               6,352,201 I See Footnotes (2) (3) (4) (5) (6) (7) (8)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction 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
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(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

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Triangle Private Holdings I, LLC
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Triangle Private Investments, LLC
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris Partners III, L.P.
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris Partners III Parallel, L.P.
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris Partners GP III, L.P.
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris GP HoldCo III, LLC
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris Capital Group III, L.P.
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris Capital Group, LLC
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris Advisor HoldCo III, LLC
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks
Siris Advisor HoldCo, LLC
C/O SIRIS CAPITAL GROUP, LLC
601 LEXINGTON AVENUE, 59TH FLOOR
NEW YORK, NY 10022
  X   X   See remarks

Signatures

 See Exhibit 99.1   08/06/2018
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) This Restricted Stock Unit Award, which was awarded to Frank Baker in connection with his service as a director of the Issuer, will vest as to 100% of the shares subject to the award on the anniversary of the date of grant, provided that Mr. Baker continues to serve as a director through such date. Pursuant to an assignment agreement between Siris Capital Group, LLC, a Delaware limited liability company ("Siris Capital Group"), and Mr. Baker, effective as of July 2, 2018, Mr. Baker has assigned to Siris Capital Group all of his right, title and interest in and to any compensation, including equity awards, he receives from the Issuer for his services as a director of the Issuer.
(2) This Form 4 is being jointly filed by and on behalf of each of the following persons (each, a "Reporting Person"): (i) Triangle Private Holdings II, LLC, a Delaware limited liability company ("Triangle Holdings II"); (ii) Triangle Private Holdings I, LLC, a Delaware limited liability company ("Triangle Holdings I"); (iii) Triangle Private Investments, LLC, a Delaware limited liability company ("Triangle Parent"); (iv) Siris Partners III, L.P., a Delaware limited partnership ("Siris Fund III"); (v) Siris Partners III Parallel, L.P., a Delaware limited partnership ("Siris Fund III Parallel"); (vi) Siris Partners GP III, L.P., a Delaware limited partnership ("Siris Fund III GP"); (vii) Siris GP HoldCo III, LLC, a Delaware limited liability company ("Siris Fund III GP HoldCo"); (viii) Siris Capital Group III, L.P., a Delaware limited partnership ("Siris Fund III Advisor");
(3) (Continued from Footnote 2) (ix) Siris Capital Group; (x) Siris Advisor HoldCo III, LLC, a Delaware limited liability company ("Siris Fund III Advisor HoldCo"); and (xi) Siris Advisor HoldCo, LLC, a Delaware limited liability company ("Siris Advisor HoldCo").
(4) Triangle Holdings II is controlled by its sole member, Triangle Holdings I. Triangle Holdings I is controlled by its sole member, Triangle Parent. Triangle Parent is controlled by its members, Siris Fund III and Siris Fund III Parallel. Each of Siris Fund III and Siris Fund III Parallel is controlled by its general partner, Siris Fund III GP. Siris Fund III GP is controlled by its general partner, Siris Fund III GP HoldCo. Siris Fund III Advisor serves as investment manager to Siris Fund III and Siris Fund III Parallel pursuant to investment management agreements with each of them. Siris Capital Group shares investment management authority in respect of Siris Fund III and Siris Fund III Parallel pursuant to an agreement between Siris Fund III Advisor and Siris Capital Group. Siris Fund III Advisor is controlled by its general partner, Siris Fund III Advisor HoldCo. Siris Capital Group is controlled by its managing member, Siris Advisor HoldCo.
(5) (Continued from Footnote 4) Each of Siris Fund III GP HoldCo, Siris Fund III Advisor HoldCo and Siris Advisor HoldCo is controlled by Frank Baker, Peter Berger and Jeffrey Hendren.
(6) The Reporting Persons may be deemed to be members of a "group" for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder (such Act and rules, as amended, the "Exchange Act"), which group may be deemed to share the power to vote or direct the vote, or to dispose or direct the disposition, of the securities reported herein. However, neither the filing of this Form 4 nor any of its contents shall be deemed to constitute an admission by any of the Reporting Persons that it is a member of a "group" for such purposes, for purposes of Section 16 of the Exchange Act or for any other purpose.
(7) Each of the Reporting Persons expressly disclaims beneficial ownership of securities held by any other person or entity other than, to the extent of any pecuniary interest therein, the various accounts under such Reporting Person's management and control. Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.
(8) Reflects securities directly held by Triangle Holdings II.
 
Remarks:
This Report on Form 4 is the first of two reports relating to the same transactions. Two separate reports were filed as a result of the 10-reporting person limitation in the EDGAR filing system. For purposes of Section 16 of the Exchange Act, the Reporting Persons may be deemed to be directors by deputization by virtue of Triangle Holdings II's contractual right to nominate directors to the Issuer's board of directors (the "Board"). Frank Baker and Daniel Moloney, each of whom was designated by Triangle Holdings II, currently serve on the Board. As a result, the "Director" box is marked in Item 5 of this Form 4.

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