I have a small Elastix 1.1-7 system with 4 extensions. No IVR. Extns 12 & 14 are in Ring Group 600 and incoming calls are sent to Ring Group 600. In the ring group settings I have set it to go to voicemail Extn 11 unavail if neither extension in the ring group answers. Exten 11 has customised voicemail messages. When I call extension 11 or ring group 600 from an internal extension the voicemail works correctly. When I call from outside I get the default message and can't find the voicemail. Can anyone suggest what is causing this?