in the agent dialer, in the spreadsheet, how can you place a 0 before the number? A regular French phone is composed like this : 01 77 88 99 All French numbers begin by 0.

You do not have to do that in the spreadsheet for every number.

Open Voicent Gateway, select Setup > Options > Outbound tab. Set “dial 0 for outside number”. Basically, you pretend you are using a PBX system that needs to dial 0 for outside line. In effect, the 0 is automatically added to every phone number in the spreadsheet.