Iu-PS interface support for UMTS RNC
In order to support 3G RAN, we would need to add an Iu interface to the SGSN.
Iu-PS over IP is specified as RANAP protocol over connection-oriented SCCP over SIGTRAN (e.g. M3UA).
Instead of having to complete a C-language connection-oriented SCCP implementation (there exists none in Free Software, irrespective of the programming language. Osmocom's erlang/osmo-sccp gets close but was never completed/tested), it might make sense to simply iplement RANAP over RUA (from the Iuh interface) instead.
It depends if we want to talk to a real RNC (Iu-PS) or if we are satisfied with Iuh as an initial step.