so it is indeed a problem .hopefully it gets sorted out as i am also facing this problem .i got this answer from gm yesterday .
"Thank you for reaching out to the Blizzard family.
Game Master Sisajobeto reporting for duty and ready to take a look at your query.
Firstly, I would like to thank you for your patience with waiting to hear back from us.
I understand that you are facing an issue adding your phone number to your account as you are not getting SMS codes. Rest assured that I have completely understood your issue and I will be working on a resolution that meets your expectations.
Since you tried the steps listed in the link you sent, and still the issue remains.
I can inform you that this is a known issue that we are already looking into it and we promise to provide a resolution as soon as possible.
I totally understand how frustrated it is to be waiting for a resolution, I will make sure this ticket is opened in case you wanted to let us know something regarding the issue, and also to make sure that we will be keeping our eyes on your account till the issue is resolved, Please accept our sincerest apologies for the inconvenience you’ve been through and all of this hassle, I completely understand your situation from a gamer to another.
Feel free to reach us whenever you need assistance.
Always glad to help 
I hope you have a good day,
GM Sisajobeto"