def METHOD_NAME(domain, monthspan):
    device_dict = {
        'cloudcare': 0,
        'sms': 0,
        'mobile': 0,
    }
    device_data = get_domain_device_breakdown_es(domain.name, monthspan)
    for device, number in device_data.items():
        if device == 'cloudcare':
            device_dict['cloudcare'] = number
        elif device == 'commconnect':
            device_dict['sms'] = number
        else:
            device_dict['mobile'] += number
    max_number = 0
    max_device = ''
    for device, number in device_dict.items():
        if number > max_number:
            max_device = device
            max_number = number
    return max_device