IMS tariff is mobile fixed line, IMS is its name
The IP Multimedia Subsystem (IMS) is a new multimedia service form that can meet the needs of end customers for more novel and diversified multimedia services.
It's essentially a network structure. This technology is rooted in the mobile field, which was originally defined by 3GPP for mobile networks, and under the framework of NGN, IMS should support both fixed access and mobile access.
3GPPR6, which covers IMS-enhanced features, has been basically frozen, which indicates that IMS technology has matured.