Exhibit 99.6

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 will 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 will 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: June 18, 2020	ALFA TELECOM TURKEY LIMITED
	By:	/s/ Maxime Nino
	Name:	Maxime Nino
	Title:	Director
Date: June 18, 2020	ATTL HOLDINGS (CYPRUS) LTD
	By:	/s/ Neil Toyer
	Name:	Neil Toyer
	Title:	Director
Date: June 18, 2020	ATTL HOLDINGS S.À R.L.
	By:	/s/ Maxime Nino
	Name:	Maxime Nino
	Title:	Manager
Date: June 18, 2020	ATTL HOLDINGS UK LIMITED
	By:	/s/ Sally Pryce
	Name:	Sally Pryce
	Title:	Director
Date: June 18, 2020	LETTERONE CORE INVESTMENTS S.À R.L.
	By:	/s/ Vitalij Farafonov
	Name:	Vitalij Farafonov
	Title:	Class I Director
Date: June 18, 2020	LETTERONE INVESTMENT HOLDINGS S.A.
	By:	/s/ Maxime Nino
	Name:	Maxime Nino
	Title:	Authorized Signatory

Date: June 18, 2020	L1T UB HOLDINGS S.À R.L.
	By:	/s/ Maxime Nino
	Name:	Maxime Nino
	Title:	Manager
Date: June 18, 2020	INTERNATIONAL MOBILE TELECOM INVESTMENT STICHTING ADMINISTRATIEKANTOOR
	By:	/s/ Nathan Scott Fine
	Name:	Nathan Scott Fine
	Title:	Director

By:	/s/ Carla Cico
Name:	Carla Cico
Title:	Director

Date: June 18, 2020	IMTIS HOLDINGS S.À R.L.
	By:	/s/ Nathan Scott Fine
	Name:	Nathan Scott Fine
	Title:	Manager