Exhibit 99.1

JOINT FILING AGREEMENT

The undersigned hereby agree that this Schedule 13D, dated July 6, 2018, with respect to the Common Stock, par value $0.01 per share, of Plantronics, Inc., a Delaware corporation, is, and any amendments hereto signed by each of the undersigned shall be, filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.

Dated: July 6, 2018

TRIANGLE PRIVATE HOLDINGS II, LLC
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Chairman
TRIANGLE PRIVATE HOLDINGS I, LLC
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Chairman
TRIANGLE PRIVATE INVESTMENTS, LLC
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Chairman
SIRIS PARTNERS III, L.P. SIRIS PARTNERS III PARALLEL, L.P.
By:	Siris Partners GP III, L.P., its general partner
By:	Siris GP HoldCo III, LLC, its general partner
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Managing Member
SIRIS PARTNERS GP III, L.P.
By:	Siris GP HoldCo III, LLC, its general partner
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Managing Member

SIGNATURE PAGE TO JOINT FILING AGREEMENT

1

SIRIS GP HOLDCO III, LLC
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Managing Member
SIRIS CAPITAL GROUP III, L.P.
By:	Siris Advisor HoldCo III, LLC, its general partner
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Managing Member
SIRIS CAPITAL GROUP, LLC
By:	Siris Advisor HoldCo, LLC, its managing member
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Managing Member
SIRIS ADVISOR HOLDCO III, LLC
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Managing Member
SIRIS ADVISOR HOLDCO, LLC
By:	/s/ Peter Berger
Name:	Peter Berger
Title:	Managing Member

SIGNATURE PAGE TO JOINT FILING AGREEMENT

2