Samantha. Our team will look into the issue you are having with the auto-recognition of your phone number. It does appear to be saved in the correct format. There are a few things from your side that might create the issue. If your phone system is VoIP or if the number you can calling from has the caller ID masked or blocked, that would create a problem with the auto-recognition as well.
If you have any issues with connecting with support or with the support portal, please send an email to supportfeedback@marketo.com. Our team handles administrative support issues and we can take action to resolve your problem.