In case someone missed it - how to remove the "+" from Mediation Server for outbound dialing.
Create text file with the following content:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key='RemovePlusFromRequestURI" value="Yes"/>
</appSettings>
</configuration>
Save it as MediationServerSvc.exe.config and place the file in the same folder where MediationServerSvc.exe is located. Restart the service.