This area holds three entities that are easy to mistake for one another.
A lead is someone who is not a customer yet — an inbound enquiry, a submitted form, a phone call. Leads are deliberately lightweight and are not expected to be complete.
A customer is the primary entity. Invoices, estimates, store orders and portal access all attach here — never to a lead or a contact. Converting a lead lands it here.
A contact is a person: someone who works for, or is associated with, a customer. It is the platform's phone book. One customer can have several contacts.
Why the customer record is so central
Every customer on this platform — a B2B account, someone who bought through the store, someone who signs in to the client portal — has exactly one record in this list.
Portal accounts used to be stored separately, which meant the same person could exist twice. Portal access is now a tab on the customer's own record rather than a separate list.
Validation is Iran-specific
Mobile numbers must match 09xxxxxxxxx, national IDs are ten digits, province comes from the 31-province list, and postal codes are ten digits. If you are importing data from elsewhere, these are the formats that will reject it.
A contact's mobile number is required — in practice it is what makes a person unique.
Duplicates
When a number or email already exists, the error names which field clashed rather than saying "this information already exists". That is deliberate: a vague message is what makes someone create a second record.