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basic services are activated (see the fig. X). Beware: the Cisco IP Voice Media Streaming App service must be activated in order to create an MTP (Media Termination Point)
- The phones (both SCCP or SIP ones) are correctly configured and functioning
- You do have a configured Calling Search Space (CSS)
- Your network design let the UDP packets to stream from the PrivateServer to the CUCMBE and vice versa
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Also check the Accept presence subscription option.