cout<<"\nDial this no.?\n "<<Name<<" "<<MobNo<<endl;
cin>>s;
if(stricmp(s,S)==0)
{
cout<<"\nDialling...\n"<<Addressbook::Name<<" "<<Addressbook::MobNo;
cout<<"\nPress END to end the call\n";
while(1)
{
cin>>s;
Are you referring to the Display() function? I suspect that the value of c isn't what you expect. Try printing it out with some temporary code or examine it in a debugger. Also, a single letter name for a global variable is a bad idea.
If PlaceCall isn't working as expected, try printing out the contents of s after you input it.
Line 21: __DATE__ and __TIME__ are not going to give you the current date and time. They are macros that resolve to the date and time of compilation.
Line 33: You haven't shown the declaration of Log.
PLEASE USE CODE TAGS (the <> formatting button) when posting code.
It makes it easier to read your code and also easier to respond to your post. http://www.cplusplus.com/articles/jEywvCM9/
Hint: You can edit your post, highlight your code and press the <> formatting button.