Hello, Some consideration would be needed:
1) SS7 for PSTN subscriber to support media-relay
2)Progress capability  for SIP subscriber.
3) Media server to support ring-back VAS service
You should check enabling this service or not during MO procedure.
With Best Regards.

On Sat, Sep 28, 2019 at 1:19 PM Maryam Baghdadi <maryam.baghdadi@gmail.com> wrote:
Hello everyone,

Is it possible to relay INVITE request to another server after receiving "180 Ringing" response ???
I would like to activate CRBT(ring back tone) service and according to my research after receiving 180 ringing media playing request should be sent to a media server .
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--Mojtaba Esfandiari.S