In the EU Boba Fett blasted and crawled his way out of the belly of the Sarlacc and didn't get help, at least none that I can remember. He fell into the pit with his weapons, helmet and jetpack so as long as he survived the initial attack by the Sarlacc's digestive system and his equipment still worked he could have used what he had to get out without transmitting a signal for help.
Not quite true. He escaped himself, I think with an explosive to blow open the Sarlaac, but he would have died in the desert without help. The bounty hunter Dengar, and a dancer named Neelah from Jabba's group that survived the sail barge, saved Fett from dying of his wounds in the desert, and then traveled with him for a while. This was told in the excellent The Bounty Hunter Wars EU book trilogy by KW Jeter. I thought the trilogy was great, and it did a good job of explaining how Boba Fett survived the Sarlaac.