When calling out, if reaching the callee I have audio and in good quality, if calling out but reach the voicemail of the callee I don’t have audio, don’t hear the any kind of voicemail (mobile, landline or any other voicemail).
Search the forum for “one-way audio” and start there. Lots of good suggestions on configuring your firewall, router, PBX, NAT, and softphone settings. It’s incredibly common and we get questions on it every week.
When you get done with the search, if you still have questions, we are going to need a lot more information to troubleshoot this.