SIP TLS is currently disabled on Linphone available for Apple store because we do not comply yet with the US exportation rules for encryption material. This is ongoing. Meanwhile, you may compile it from the source to have access to the full functionality set.
Are you sure the old version worked? I have been trying on Linux with no joy, I think the only platform it works on is windows.
The old version on iPhone worked (took a little messing with config files and certs) but the latest version doesn't. We're not in a position here to recompile on iOS at present so we're kind of stuck...
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