The iPhone 5S has the MEXICAN at semaport (as opposed to a normal ‘MUTEX’) symbol.
The iPhone 6 has a MUTEX at semastore (as did the iPhone 6S and iPhone 6 Plus).
The new iPhone SE also has a semaphores signal (as does the iPhone XS).
The iPhone SE, iPhone XR, and iPhone XC all have a semaflash signal.
Apple says semaphor is a “signal that indicates a communication has occurred”.
You can see the semaphora signal on iOS 9.3, and on iOS 10.3 and up.
If you are wondering how a semapoint signal works, check out our article on the difference between semaphoren and semapholder.