ZTE has completed a series of tests between TD-LTE and 2G/3G GSM/UMTS networks using 3GPP circuit switching fallback (CSFB).

 The operations included testing a series of services such as mobile originating calls, mobile terminating calls and short messaging service, or SMS.The tests demonstrate that CSFB is a reliable voice solution on TD-LTE networks, company said in a statement.

When a user on a phone using CSFB that operates on an LTE network initiates a voice call, the CSFB handset will “fall back” to available 2G/3G networks to complete the call. CSFB allows greater call range as it uses existing 2G/3G nodes. This use of existing infrastructure also enables voice services without IMS deployments.