diff --git a/cmd/callsign.go b/cmd/callsign.go
index 56f606e..46e1dbc 100644
--- a/cmd/callsign.go
+++ b/cmd/callsign.go
@@ -42,20 +42,28 @@ func ValidateCall(sign string) (call, errorMsg string) {
 		if validCallRegexp.MatchString(sp[0]) {
 			//Callisign with suffix (unchecked)
 			return sign, ""
-		} else {
-			//Callsign with prefix
-			//validate the part that should contain the call (sp[1]) 
-			if !validCallRegexp.MatchString(sp[1]) {
-				return wrongSign, "Invalid call"
-			}
-			//validate the prefix
-			if !validPrefixRegexp.MatchString(sp[0]) {
-				return wrongSign, "Invalid prefix"
-			}
-			return sign, ""
+		} 
+		//else we are dealing with a prefixed Callsign
+		//validate the part that should contain the call (sp[1]) 
+		if !validCallRegexp.MatchString(sp[1]) {
+			return wrongSign, "Invalid call"
+		}
+		//validate the prefix
+		if !validPrefixRegexp.MatchString(sp[0]) {
+			return wrongSign, "Invalid prefix"
 		}
+		return sign, ""
 	case 3:
-		return sign, "??????"
+		//validate the part that should contain the call (sp[1]) 
+		if !validCallRegexp.MatchString(sp[1]) {
+			return wrongSign, "Invalid call"
+		}
+		//validate the prefix
+		if !validPrefixRegexp.MatchString(sp[0]) {
+			return wrongSign, "Invalid prefix"
+		}
+		//We don't check the suffix
+		return sign, ""
 	}
-	return sign, "?????"
+	return wrongSign, "Too many '/'"
 }
\ No newline at end of file
diff --git a/cmd/callsign_test.go b/cmd/callsign_test.go
index 9bb5e66..ac40c59 100644
--- a/cmd/callsign_test.go
+++ b/cmd/callsign_test.go
@@ -15,45 +15,63 @@ func TestValidateCall(t *testing.T) {
 		{
 			"Good call (simple)", 
 			args{ sign: "on4kjm", }, 
-			"ON4KJM", 
-			"",
+			"ON4KJM", "",
 		},
 		{
 			"Good call (suffix)", 
 			args{ sign: "on4kjm/p", }, 
-			"ON4KJM/P", 
-			"",
+			"ON4KJM/P", "",
 		},
 		{
 			"Good call (prefix only)", 
 			args{ sign: "DL/on4KJm", }, 
-			"DL/ON4KJM", 
-			"",
+			"DL/ON4KJM", "",
 		},
 		{
 			"Good call (prefix and suffix)", 
 			args{ sign: "DL/on4KJm/p", }, 
-			"DL/ON4KJM/P", 
-			"",
+			"DL/ON4KJM/P", "",
+		},
+		{
+			"Good call (Numerical prefix)", 
+			args{ sign: "4x/on4KJm/p", }, 
+			"4X/ON4KJM/P", "",
+		},
+		{
+			"Good call (prefix and long suffix)", 
+			args{ sign: "DL/on4KJm/qrpp ", }, 
+			"DL/ON4KJM/QRPP", "",
 		},
 		//Error cases
 		{
 			"Pure junk passed", 
 			args{ sign: "aaaaaa", }, 
-			"*AAAAAA", 
-			"Invalid call",
+			"*AAAAAA", "Invalid call",
 		},
 		{
 			"empty string", 
 			args{ sign: "", }, 
-			"*", 
-			"Invalid call",
+			"*", "Invalid call",
 		},
 		{
 			"string with spaces", 
 			args{ sign: "  ", }, 
-			"*", 
-			"Invalid call",
+			"*", "Invalid call",
+		},		
+		{
+			"invalid prefix", 
+			args{ sign: "xyz/on4kjm", }, 
+			"*XYZ/ON4KJM", "Invalid prefix",
+		},
+		{
+			"Too many /", 
+			args{ sign: "F/on4kjm/p/x", }, 
+			"*F/ON4KJM/P/X", "Too many '/'",
+		},
+		{
+			"signe /", 
+			args{ sign: "/", }, 
+			"*/", "Invalid call",
 		},
 	}
 	for _, tt := range tests {