My Post parameter is :

JSONString={"contact_name": "Test","contact_type": "customer","gst_treatment": "business_none","gst_no": "","billing_address": { "country": "India" },"shipping_address": { "country": "India" },"contact_persons": { "phone": "123123123","is_primary_contact": "true" }}&organization_id=

I do not find any issue with the JSON. How to fix this?