Does IMS allow VoLTE calls setup on default bearer?

Dear Experts.

Does IMS allow VoLTE calls setup on default bearer?

For example when PCRF is faulty, bypass PCRF, no dedicated bearer.

For emergency, it is ok, accept voice quality down. But is it ok VoLTE calls on default bearer?

I’ve heard Huawei IMS can do this…

Yes volte can be done on default bearer.