Did you (the caller) set the correct SIP URI (phone number)?
Has the callee registered to Brekeke SIP Server? Or, is the dial plan set correctly to route a call to the callee?（ If you are also using Brekeke PBX please check the ARS rules and the User settings）
Please check Brekeke SIP Server’s local port number. The default port number is 5060. When you use a number besides port 5060, there is a possibility that it does not work properly depending on the type of UA or gateway you choose.
If you are trying to access Brekeke PBX voicemail system or auto attendant, the default prefix settings are 06* (IVR), 07* (VM), and 08* (MSG). Please check the dialing number is correct.