Good day! Try to send sms from magento and SMS Nitfier.
1. To russian number 79817487722 sms sended from magento correct. I could see them in atrio logs. But dont recieve it to the phone.

2. With finnish number sms not sended from magento: SMS to could not be sent. Reason: 'Number is not set.'
I try diferent variants to type the number with same result!
3580504416737
358504416737
358 50 441 67 37
504416737 (aftomaticaly addded 358)

Hello,

1. Our provider reports a problem with delivering your messages to 79817487722. We've contacted them to find out what the reason is. Once we get a response, we'll let you know.

2. The error means that the phone number is not entered correctly in the order. Please check that your magento order contains the phone number in a correct field. Or please post a screenshot of the problem. Thank you.

Hello,

Our provider reported that for the phone number 79817487722 they've got a response of "Network error". They suggested that you should check with your service provider whether the phone number is active.
If the phone number is correct and active, we may investigate further with them what the problem is.