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) The system does not classify these or track them, as far as I know. Although it is possible the multi-lead auto-alt-number dailing system may use one of them.
Auto Alt-Number Dialing - This setting is used to automatically dial alternate number fields while dialing in the RATIO and ADAPT dial methods when there is no contact at the main phone number for a lead, the NA, B, DC and N statuses. This setting is not used by the MANUAL dial method. EXTENDED alternate numbers are numbers loaded into the system outside of the standard lead information screen. Using EXTENDED you can have hundreds of phone numbers for a single customer record. Using MULTI_LEAD allows you to use a separate lead for each number on a customer account that all share a common vendor_lead_code, and the type of phone number for each is defined with a label in the Owner field. This option will disable some options on the Modify Campaign screen and show a link to the Multi-Alt Settings page which allows you to set which phone number types, defined by the label of each lead, will be dialed and in what order. This will create a special lead filter and will alter the Rank field of all of the leads inside the lists set to this campaign in order to call them in the order you have specified.