The Emergency Telephone (ZG15) safety sign has a white telephone on the green square shaped safety sign.
 
The sign indicates where there is a telephone dedicated to making calls to emergency services and it's most often found in a place of special danger or where it is likely that there will only be a need to make emergency calls.
The fire telephone safety sign should be placed near the fire telephone, preferably with an emergency telephone list.  
SABS standard safety sign