Huawei has announced that it enabled circuit switch fall back (CSFB) voice call between a LTE TDD compatible network and a UMTS network. This CSFB voice call was made through Huawei's STREAM 201HW smartphone, now available through SOFTBANK MOBILE Corp in Japan. Huawei's STREAM 201HW has a customized Qualcomm Integrated Circuit (IC) chip that supports both LTE TDD (AXGP) and UMTS.

To complete the call, the AXGP (Advanced eXtended Global Platform) network was connected with the UMTS network of SOFTBANK MOBILE. AXGP is a network compatible with the LTE TDD of Wireless City Planning Inc., a SoftBank Group company.

CSFB enables the delivery of circuit-switched voice and short message services to LTE devices. When an LTE handset makes or receives a voice call, the device ‘falls back' to a UMTS network to complete the call. This feature is necessary if operator's LTE network does not support VoLTE calls.

During trials in India August last year, Huawei completed multiple live handover scenarios across GSM/UMTS/LTE.