How to send to multiple phone numbers at once with content created action?

I've got everything working and am able to send out a message to one number at a time. The way I'm doing it is, I've created a content type with just one text field for phone number. Then I using Rules, whenever there is a node created with that content type (i.e. phone number of recipient), an SMS is sent to that phone number. However, when I try to add multiple phone numbers by creating additional fields, the module gives me an error and says Twilio has returned the error: "The 'To' number +1714478****, 949464**** is not a valid phone number." For some reason, it doesn't put the country code number 1 in front of any other number except for the first number and also doesn't recognize them as two separate phone numbers, just one long string of one phone number. How do I fix this?