At some point in the future we want to support CDMA networks. We need to validate the server API and make sure the clients implement this.
The API was extended to support CDMA networks. Description at https://mozilla-ichnaea.readthedocs.org/en/latest/cell.html#cdma On the server side, we need to figure out how to do multilateration for CDMA networks.
We implemented this in MozStumbler in https://github.com/dougt/MozStumbler/pull/182, which is the only current client. If we take up development of other clients again, we'll file separate bugs for those.