Opération Lybie has organized a bunch of dialup numbers for Lybian citizens to use in case the government cuts off their internet access (see the similar effort at using POTS lines for Tweeting in Egypt).
I'm relaying a message from a Libyan citizen, who came on IRC channel #FDN to talk about opération "Libya White Fax".
The idea is to send a PDF document to the Libyan population via FAX (using traditional FAX or SIP) to a given list of Libyan phone numbers.
The faxed document contains a list of international phone numbers for dialup users to access so they can get back on the Net. Obviously this will be expensive, but it'll get around the "Internet Kill Switch" strategy.
One dialup service donor is France's FDN. Here's their statement (they started offering dialup during the Egyptian crisis).
Now I kind of wish I hadn't trashed all my old modems... who knows when we'll need these again?
Opération Lybie (scroll down for English)
We Rebuild's Libya page has broader information on infrastructure and counter-censorship.