1. Create a CSV file using this format:
NOTE: It is very important to include an External ID as this will serve as a reference key to ensure that the Contacts belong to the same Company. Please be noted that External ID acts the same as the Internal ID. The only difference is that the External ID is assigned by the user while Internal ID is assigned by the system. Hence, if you wish to update an existing record that you have imported in NetSuite with an External ID, you may use this also as a reference key. It would be best to keep the CSV files if in case you need to update some records in the future.
An External ID can be numeric, alphabet, or alpha-numeric i.e. 123, abc, or abc123.
2. Set Up> Import/Export> Import CSV Records
3. Import Type=Relationships; Record Type=Leads and Contacts Together> Select the File> Hit Next
4. Data Handling=Add > Hit Next
5. Mapping as below:
6. Hit next
7. Enter Import Map Name> Save and Run> Hit Import Job Status> Refresh