Many foreign providers prefer payment from the patient when services are rendered. If you contact a doctor or hospital before you go for a visit, CISI can arrange a "guarantee of payment" so that you may not need to face out of pocket costs.
If you go to a medical provider who is a preferred vendor of CISI, they may be able to directly bill CISI, which means you will not need to pay out of pocket for what the insurance covers.
If you go to a medical provider who is not preferred vendor of CISI, you will need to pay out of pocket first and file a medical claim for reimbursement. You will be required to submit an itemized bill in order for CISI to process the claim so make sure to get the itemized bill from your health care provider.