Why 2 separate entries for each call?

Why does voicemail list each call as 2 separate calls:
1st call is usually 7sec long to provide phone number of the caller.
2nd call is the message itself.
any reason for it?

Just to be clear about the issue: are you seeing calls sent to voicemail being listed as two entries in the call log?

YES… both in the call log and on the answering machine
ONE to tell who is calling (ID), and the time - 7sec
TWO: the message itself.

PS: I forward my calls to a Google #; if that has anything to do with it?!

Is your GV also forwarded to your Ooma?

Yes…Thanks… I just cancelled (GV Fwrd to Ooma) to see if that was the cause.
but then, I may not get a voicemail on Ooma?..