You will not be able to integrate multiple Salesforce organizations into one company ID.

You can integrate one Salesforce organization into multiple company IDs.

In this case, you would need to download a call center definition file from MiiTel Admin of each company ID. After you download the call center definition files, please import them to Salesforce. For instructions on how to receive and set a call center definition file, please check Salesforce Softphone Deployment.