Getting ORA-29024&ORA-29273 for https request

I got email from one of our customer. He says they have been changed their SMS system and they want to use https. But when they try to get select query return with below error message

ORA-29273: HTTP request failed
ORA-06512: at "SYS.UTL_HTTP", line 1572
ORA-29024: Certificate validation failure
ORA-06512: at line 1

I tried below query and get same error:

Select utl_http.request('https://smsservice.tuzla.bel.tr/SmsProxy.asmx') from dual;

After I investigate error I found Tim’s blog post. You can click here to get more details about his post.

What I do? Here are my steps: