1. AT&T Ltd.
2. Bharti Airtel Limited
3. Cisco Systems Inc.
4. Huawei Technologies Co. Ltd.
5. Mavenir Systems Inc.
6. MessageBird BV
7. Orange S.A.
8. Ribbon Communications US LLC
9. Route Mobile Limited
10. Sinch
11. Telefonaktiebolaget LM Ericsson
12. Telefonica S.A.
13. Twilio Inc.
14. Verizon Communications Inc.
15. Vodafone Group PLC
16. Vonage