Exhibit 99.4

JOINT FILING AGREEMENT

PURSUANT TO RULE 13d-1(k)

The undersigned acknowledge and agree that the foregoing statement on Schedule 13D is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13D shall be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate.

Date: November 9, 2015
	ALFA TELECOM TURKEY LIMITED
	By:	/s/ Franz Wolf
	Name:	Franz Wolf
	Title:	Director
	ATTL LIMITED
	By:	/s/ Franz Wolf
	Name:	Franz Wolf
	Title:	Director
	ATTL HOLDINGS A SOCIÉTÉ À RESPONSABILITÉ LIMITÉE
	By:	/s/ Vitalij Farafonov
	Name:	Vitalij Farafonov
	Title:	Manager
	ATTL HOLDINGS UK LIMITED
	By:	/s/ Hugo Canwell
	Name:	Hugo Canwell
	Title:	Director
	LETTERONE INVESTMENT HOLDINGS S.À R.L.
	By:	/s/ Maxime Nino
	Name:	Maxime Nino

Title:	Manager
LETTERONE HOLDINGS S.A.
By:	/s/ David Gould
Name:	Dave Gould
Title:	Class I Director