I would say that those guys were very lucky. No mention of why the boat capsized--seas do not look that rough in the photo.
The other issue is the fact that a cell phone even worked--somehow it must have been kept out of the water, and was within range.
I prefer to have a personal locator beacon (getting cheaper all of the time--has GPS and direct line to CG for rescue from Sat Sar.) Then add in a waterproof, hand held VHF radio--all kept on your person.
Hypothermia can set in fast in those waters.