[xVIP3Rx]

Try this

pawn Код:

CMD:callsign(playerid, params[])
{
    if(IsPlayerInVehicle(playerid)) return SendClientMessageEx(playerid, COLOR_GREY, "You're not in a vehicle.");
    if(!IsACop(playerid) || !IsALVMPDCop(playerid) return SendClientMessageEx(playerid, COLOR_GREY, "You must be a police officer.");

    new vehicleid = GetPlayerVehicleID(playerid);
    
    if(!IsACopCar(vehicleid)) return SendClientMessageEx(playerid, COLOR_GREY, "You must be inside a police cruiser.");
    
    if(vehiclecallsign[GetPlayerVehicleID(playerid)] == 1)
    {
        Delete3DTextLabel(vehicle3Dtext[vehicleid]);
        vehiclecallsign[vehicleid] = 0;
        SendClientMessage(playerid, COLOR_RED, "Callsign removed.");
    }
    else
    {
        new string[32];
        if(sscanf(params, "s[32]",string)) return SendClientMessageEx(playerid, COLOR_GREY, "You must enter a callsign.");

        vehicle3Dtext[vehicleid] = Create3DTextLabel(string, COLOR_WHITE, 0.0, 0.0, 0.0, 10.0, 0, 1);
        Attach3DTextLabelToVehicle(vehicle3Dtext[vehicleid], vehicleid, 0.0, -2.8, 0.0);
        vehiclecallsign[vehicleid] = 1;
    }
    return 1;
}

I optimized it a bit