Hi Cansu,
Here are a few community posts in which it appears that some folks were able to get this working:
SMS integration with SD 12.9
CA SDM r12.9 integration with SMS Gateway (HTTP Post)
Please note that it does appear to require some custom code, which is something that is outside the scope of support, however some folk son the community have shared some files.
Hope these can help you out a bit.
Jon I.