How to get department id?

I am trying "Edit Call Queue Members", for this department ID is must. <br>i tried with extension id but not working,

<img src="https://d2r1vs3d9006ap.cloudfront.net/s3_images/1723515/RackMultipart20180409-25616-14kmywf-Capture_inline.PNG?1523273095" title="Image: https://d2r1vs3d9006ap.cloudfront.net/s3_images/1723515/RackMultipart20180409-25616-14kmywf-Capture_inline.PNG?1523273095"><br>{    "errorCode": "EXT-400",    "message": "Not a department extension",    "errors": [      {        "errorCode": "EXT-400",        "message": "Not a department extension"      }    ]  }