1) Welcome to the Party!
2) As you are obviously new here, I have some suggestions to help us all help you:
When you post, please post your entire configuration including (but not limited to) your installation method and vicidial version with build.
This IS a requirement for posting along with reading the stickies (at the top of each forum) and the manager's manual (available on EFLO.net, both free and paid versions)
You should also post: Asterisk version, telephony hardware (model number is helpful here), cluster information if you have one, and whether any other software is installed in the box. If your installation method is "from scratch" you must post your operating system and should also post the .iso version from which you installed your original operating system. If your installation is "Hosted" list the site name of the host.
If this is a "Cloud" or "Virtual" server, please note the technology involved along with the version of that techology (ie: VMware Server Version 2.0.2). If it is not, merely stating the Motherboard model # and CPU would be helpful.
Similar to This:
Vicibox X.X from .iso | Vicidial X.X.X-XXX Build XXXXXX-XXXX | Asterisk X.X.X | Single Server | No Digium/Sangoma Hardware | No Extra Software After Installation | Intel DG35EC | Core2Quad Q6600
3) dial code occurs after country and before phone number. so 00 this is not "dial code" unless 33 is part of your phone numbers (all of them? LOL) instead of being a country code.
4) if you modify your dial command in admin->carriers->[choose]->Dialplan Entry ... you can force the "00" into the dialed number to your carrier without it being part of the phone number or dial code.
Example of a normal dial line from the dialplan entry:
exten=>_81NXXNXXXXXX,n,Dial(${DIAL8TRUNK}/${EXTEN:1},,To)
Here is that same one with "00" forced before the dialed number to the carrier (fairly simple, really):
exten=>_81NXXNXXXXXX,n,Dial(${DIAL8TRUNK}/00${EXTEN:1},,To)
This will allow you to set your dialplan entry to 33XXXXXXXXX (which may match your numbers being dailed ...) while dialing 0033XXXXXXXXX to the carrier if that is your requirement.
5) You can also modify your Campaign Dial Prefix to "00" which will put 00 in front of the numbers being dialed.