Bypassing VOIP ISP block in Asterisk
![Image](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCRutPhuxItCJ8uLo20ISaH7pNE7W0ZT10b_Bur1m01oI70n7JqgHQ7x1ltlVRvfx9PNkMWjkpZ2aRkX-BPVaiyVDoT2Wet2_NIR-xhAJ5gfZVbxrWIRO6G65n3uhYkYZ65VRaSL7ks_0/s400/sip.jpg)
This is an article I shared before on my LinkedIn profile a while ago, but I decided to re-share it on my blog with minor changes. You can find the LinkedIn article here . Introduction I was a new guy to Asterisk. I set up my users, my dialplan and everything seemed fine, until I wanted to let my users connect to my server from the internet. I set up port forwarding on my router, but when I tried to connect from an internet device, nothing would happen. Living in Egypt, I discovered that my ISP is blocking SIP. Attempting to use SIP over UDP port 5060 (which is the default) always resulted in failure. I decided to change the port number, tried again but to no avail. I also tried SIP over a random TCP port but it still did not work. I concluded that my ISP blocks SIP using deep packet inspection. So I did some research, read some RFCs (Request for comments) and I will share here the concepts I learnt and how they helped me get over these restrictions. Please know that thi