annex Modeulation IN DSL line

https://networkdream.ir/1394/03/28/%D9%85%D9%81%D9%87%D9%88%D9%85-annex-%D8%AF%D8%B1-%D8%AA%DA%A9%D9%86%D9%88%D9%84%D9%88%DA%98%DB%8C-adsl/