Joint Filing Agreement

EXHIBIT 21

Joint Filing Agreement

In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing of NTOP Holdings, L.L.C., IDT Domestic-Union, LLC, IDT Investments Inc., IDT Nevada Holdings, Inc., IDT Domestic Telecom, Inc., IDT Telecom, Inc., IDT Corporation and Xxxxxx X. Xxxxx on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to shares of Common Stock, par value $0.01 per share, of Net2Phone, Inc., and that this Agreement be included as an Exhibit to such joint filing. This Agreement may be executed in any number of counterparts all of which taken together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned hereby execute this Agreement this 3rd day of December 2003.

IT STOCK, LLC
By:		NTOP Holdings, L.L.C., its member
		By:		/s/    XXXXX X. XXXXX
				Name:		Xxxxx X. Xxxxx
				Title:		Manager

NTOP HOLDINGS, L.L.C.
		By:		/s/    XXXXX X. XXXXX
				Name:		Xxxxx X. Xxxxx
				Title:		Manager

IDT DOMESTIC-UNION, LLC
By:		IDT Domestic Telecom, Inc., its managing member
		By:		/s/    XXXXX XXXXXXXXXXXX
				Name:		Xxxxx Xxxxxxxxxxxx
				Title:		Chief Executive Officer

IDT INVESTMENTS, INC.
		By:		/s/    XX XXX
				Name:		Xx Xxx
				Title:		Acting President

IDT NEVADA HOLDINGS, INC.
		By:		/s/    XX XXX
				Name:		Xx Xxx
				Title:		Acting President

IDT DOMESTIC TELECOM, INC.
		By:		/s/    XXXXX XXXXXXXXXXXX
				Name:		Xxxxx Xxxxxxxxxxxx
				Title:		Chief Executive Officer

IDT TELECOM, INC.
		By:		/s/    XXXXX XXXXXXXXXXXX
				Name:		Xxxxx Xxxxxxxxxxxx
				Title:		Chief Executive Officer

IDT CORPORATION
		By:		/s/    XXXXX X. XXXXXXX
				Name:		Xxxxx X. Xxxxxxx
				Title:		Chief Executive Officer

/s/    XXXXXX X. XXXXX

Xxxxxx X. Xxxxx