Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I want to find out whether or not my ISP is blocking the ports 5050 and 6060 which I need for my voip software on my iPhone. I'm using a 3G stick with a prepaid plan, and I'm using the internet sharing option on my mac to get internet on my iPhone through my macbook's wifi.

And if not, I'm looking for a way to get my voip software working.

share|improve this question

Use this site. Enter the port number you want to check and click Check.

share|improve this answer
If you're not running a service on that port, it also says the isp is blocking the port.. However, I quickly made a java application to listen on port 5050 and 6060 and it seems like the isp isn't blocking the ports... – Sander Declerck Jan 9 '12 at 19:48
Hm, that's odd. It doesn't say anywhere on the site that a service needs to be running. So your java app solved your problem? – SaintWacko Jan 9 '12 at 19:52

Open a terminal. Try the following commands, replacing the portion in brackets with the server name or IP of your VoIP server:

telnet [voip server name or ip] 5050
telnet [voip server name or ip] 6000

If it is blocked, telnet will not connect (you'll receive an error about this immediately or after a brief moment).

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.