Specific to India
LabSmart lets you download patient contacts which you can use to run your SMS campaigns. To send bulk SMS in India you need comply by TRAI guidelines and need to follow a process. It could take a week or more before you can complete the process and start sending SMS to your contacts. There are many services providers which can help you with this process and let you send bulk SMS, you can find them by searching for "bulk sms service" on Google. Eg. Textlocal , MSG91 and many others.
How it works?
You can do the same for referrers. Download referrers option is available on referrers page.