June 14, 2007 Ms. Linda Krysieniel, Facilities and Travel Manager NMS Communications Corporation

Exhibit 10.26

June 14, 2007

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NMS Communications Corporation

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Dear Friends:

Pursuant to the Third Sublease Agreement Amendment dated April 21, 2006, amending the Sublease Agreement between our two companies dated October 30, 2002, as previously amended (the “Sublease”), GlassHouse Technologies, Inc. has an option to extend the Term of the Sublease for an additional one year period commencing December 1, 2007, at an Annual Fixed Rent of $ 252,126.

Please accept this letter as our notice, pursuant to Section 19 (d) of the Sublease, to exercise such option and extend the term for an additional year commencing December 1, 2007, at the Annual Fixed Rental of $ 252,126.

We appreciate the good landlord–tenant relationship that we have enjoyed and look forward to its continuation.

Kindly sign and return the enclosed copy of this letter to acknowledge your receipt of this notice.

Thank you for your consideration.

Sincerely yours,
GlassHouse Technologies, Inc.
By:		/s/    ▇▇▇ ▇▇▇▇
		▇▇▇ ▇▇▇▇, Chief Financial Officer

Receipt Acknowledged
NMS Communications Corporation
By:		/s/    ▇▇▇▇▇ ▇▇▇▇▇
Title/Date:		Vice President June 14, 2007

cc: NMS Communications Corporation

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Attn: VP & General Counsel