Form not submitted while the sms is enabled

[nikpony]

Hello, in my customer's site as i am testing, it doesn't work. To be more specific, mail is sending but the form not submitting. The loading icon keeps cycling and of course sms not sending also.
I have tried to uninstall all other plugins and extra javascript code, also to turn to the default theme but none of them makes me happy.
Could you help me please? Thanks in advance.
In console the error that displays is the attached one.