I’ve explained this in twitter, but here is the basics of how it works.

Telephone systems are designed to allow a fraction of people to communicate at any given time. When the system overloads, you get busy signals or system announcement that lines are temporarily busy.

To make a system busy YOU DON’T HAVE TO CALL ANYONE. All you have to do is get a dial tone.

Most well designed systems max out at 15% usage. Typical systems in Iran cap out at 3-4% usage. This means if 10% of people in a switch are lift their phone of the receiver and get a dial-tone, it brings down phone service in that part of town

HOW
• Agree on “OFF HOOK” time.
• Agree on “RESTORE” time

1) lift phone off the hook/receiver. If you get a dial tone, great, if not, it means others have begun to “OFF HOOK”. Just keep trying

2) When you get a dial tone, monitor it every few minutes. If your tone goes away, hang up and retry.

3) replace phone back on hook when protest is over -RESTORE.

WHY
This protest is especially effective as it brings down phone and fax and DSL. It should be targeted in neighborhoods near Majlis, vezarat-khaneh (ministries), police HQs, TV and Radio, etc.

Bringing land lines down forces everyone to go mobile. And there is insufficient capacity for that. Not to mention, when you fear that mobile service will be shut down, this is the best way to make sure they turn it back on.