Don't have Telegram yet? Try it now!
http://sitak.co/2018/03/04/%d8%aa%d9%81%d8%a7%d9%88%d8%aa-voip-%d9%88-%d8%b3%d8%a7%d9%86%d8%aa%d8%b1%d8%a7%d9%84-%d8%a2%d9%86%d8%a7%d9%84%d9%88%da%af/
تفاوت voip و سانترال آنالوگ