Without the ability to connect to non-VoLTE-enabled operators, 4G- and 5G-only operators will lose much of their roaming partnership business.

Most importantly, by losing this voice service business with non-VoLTE operators, they also lose data service business as well. This results in significant lost roaming business for operators as well as less roaming market competition for consumers, which means higher roaming rates.

The outbound roaming MNO will have less choice of which networks they can roam on, potentially impacting their service quality and higher rates.

If a roaming subscriber connects to a visited network that also no longer supports 3G, the subscriber then must have a VoLTE-enabled device, and their home network must also support VoLTE, in order for them to make a voice call and subsequently use data over that device while roaming.

Evolved Mobility allows 4G- and 5G-only operators to support 3G fallback, making these calls via VoLTE and thus, allowing users on non-VoLTE networks to make VoLTE-powered calls.