Workflow SMS function in zoho creator

Workflow SMS function in zoho creator

I am trying to setup an Zoho crm workflow that calls a custom function to send a sms message using twilio. 

The function is as follows: 

void sms (string Phone)
{
sms_response = twilio.sms.send("Twilio","5455544454","tester");

}


I want to use the input variable in place of the phone number but for testing i have just put my mobile phone number here.

This does not seem to send anything. This same function works in zoho creator but does not work in zoho crm as a custom function. Is this a limitation of zoho crm?  Is there a work around?