E-CID might also work as a fallback method, when more precise positioning provided by other techniques, such as A-GNSS, is inaccessible, either due to UE limitations (no built-in GNSS receivers) or due to unavailability of GNSS signals (e.g., the target UE is indoors).
A-GNSS. LTE A-GNSS effectively is not just A-GPS: it also supports the Russian GLONASS  and is designed to be forward-compatible with future constellations (e.g., Galileo, still not fully operational).
It supports E-CID, A-GNSS, and OTDOA, as well as hybrid localization to improve accuracy.
In addition, Rohde & Schwarz announced that CETECOM, a specialist in test and certification for wireless communications devices, has selected the R&S TS8980FTA-2 and R&S CMW500 wireless test platforms for conformance and network-operators acceptance testing for LTE RIO CA, IMS, VoLTE, RCS, E911 over IMS, A-GNSS, OTDOA, and eCID.
Both organizations will use the platforms to support technologies such as CA, VoLTE/IMS, RCS, A-GNSS, OTDOA, eCID, and E911 over IMS.