A .csv file with a list of contacts and their properties. The .csv file must include a header with the columns names. The file must contain EITHER the 'phoneE164' column OR the 'countryCode' and 'phone' columns. The columns that are read: - phoneE164: contact's phone in E.164 format (e.g., +34666112233). - countryCode: must be an integer, e.g. 34. - phone: e.g. 666112233. - externalCode: e.g. user123. Optional. - enabled: must be 1 or 0. Optional. Example 1, using phoneE164: ~~~ phoneE164,externalCode,enabled +34666112233,user123,1 +447700900123,user124,1 +12025550104,user125,0 ~~~ Example 2, using countryCode and phone: ~~~ countryCode,phone,externalCode 34,666112233,user123 34,666112244,user124 ~~~