Virtual Office voicemails are landing in cellular provider's voicemail system.
Your Virtual Office voicemail system timeout is shorter than the cellular timeout interval. As a result, when you are unable to answer a call on your L'application mobile Virtual Office, the cellular voicemail picks up.
If you are using Call Mode > Inbound > Use Cellular voice, and missed calls to your Virtual Office number are being incorrectly answered by your cellular provider's voicemail, you should decrease the time when you do not answer a call before Virtual Office voicemail picks up.
Virtual Office voicemail should now answer missed calls before your cellular provider's voicemail picks up. If your cellular provider's voicemail is still picking up missed Virtual Office calls, see the following page about increasing your cellular provider's time before sending to voicemail:
http://lifehacker.com/5878635/change-how-long-your-phone-rings-before-sending-calls-to-voicemail