WiFi Doorbell to Smartphone

As connectivity to the home improves via new internet connection technology and smart phones become ubiquitous it is a natural extension to connect to your home through your smart phone.  A WiFi door bell that connects to your smart phone sounds easy and cost effective – Early adopters of technology have been connected for some time and now this idea has started to become mainstream.

It all seems simple enough: you have a WiFi router in your home with high speed internet connection and have a smart phone with decent broadband which also has WiFi.  While at home the phone is on the same WiFi access point (LAN) making sharing data easy and fast.  When away from home the data uses the home internet connection (WAN) to reach your smart phone via the phone broadband connection.  Simple, right?

There are a number of technology hurdles with the scenario above and as long as you understand them there are work arounds:

1. Network switching between WiFi local LAN and WAN (smart phone on broadband via mobile carrier) is problematic.  This is mainly when leaving or entering the WiFi network that the issue occurs.  
2. Internet uplink connection speeds are usually much lower than downlink speeds restricting the amount of data that can use the uplink at at any time.  This is not an issue as it once was with ADSL and is much improved with NBN and 5G
3. Connection to local WiFi (see below) may not occur until the door station wakes up and negotiates an IP address (DHCP) which delays the connection.  This is prevalent on battery powered door stations as they preserve power by turning off WiFi but generally is not an issue with a powered system (not battery).

The first issue is usually resolved by making all connections between the smart device (door bell in this instance) via a remote server on the internet.  The smart phone is registered to the same server and the data is pushed from the door bell to the smart phone whenever a call is made, even when the phone is connected to WiFi.  This greatly simplifies the networking but invokes a new suite of issues:

1. The system uses 2 internet connections to provide the connection – home broadband and mobile broadband. This can result in large data use charges especially with video. Most mobile broadband plans can deal with this and the video stream is usually fairly low throughput due to small screen sizes. 
2. The time to establish the call and quality of the call are dependent on the round trip distance and network congestion – door bell via WiFi to router, router via restricted uplink to internet, path from home ISP to mobile provider, downlink from mobile provider via multiple phone towers to moving device.

There is one more impediment to a good connection which will effect any device connected via WiFi: WiFi network quality.  The door bell location will be on the outside of the home with a solid wall between it and the internal WiFi network.  The door bell will most likely be battery operated so no cables are required (if you have to run power then why would you not use an ethernet connection as well with power over ethernet?).  The low power consumption requirements will limit the transmit power of the inbuilt WiFi radio and therefore reduce the speed and reliability of the WiFi connection.  The remedy for this issue is a WiFi extender close to the entry with the door bell or use a good WiFi mesh system with improved coverage.

To conserve power the (battery powered) door bell will wake up on button press or detection of a visitor, connect to the WiFi router most probably via DHCP which may take some time to allocate an IP address, connect to the remote server and begin data transfer, while playing the ring tone to the visitor via the inbuilt speaker so they know the call is proceeding.   The time taken for these steps may be 20 seconds and meanwhile the call has not made it to the smart phone.  Allow another 5-10 seconds assuming the smart phone is at hand and the user is available for the call to be answered.  These times are average and systems will vary.  The result will depend on the patience of the visitor – anecdotes from customers suggest that many calls will be answered to an empty doorway as the visitor has left.  A powered door station will not have these long delays as the radio is connected at all times. 

Where the system uses all WiFi components the issues with network quality are magnified.  If you live in a built up area (lots of WiFi), if you have lots of WiFi connected devices (tablets, phones, computers, gaming consoles, printers, other WiFi connected devices) or you live in a home with multi-levels or solid walls (reflections), we recommend you only look at wired solutions.  The system may work initially but will become more unreliable over time due to spectrum congestion.  Upgrading the WiFi network to a mesh system will help with WiFi quality and is a worthwile addition.

In summary, while a WiFi door bell to smart phone sounds like a good and easy solution to allow remote monitoring of visitors, the end user experience may not be as expected.  These systems may be quite cost effective but are let down by power, time to connect, and call quality.  If cost is the main driver then these systems are worth trialing but please be aware that it is a case of buyer beware.  We recommend hard wiring in all instances or using cabled power to keep the door station powered and connected to the WiFi router.

We do offer a WiFi door station system that performs quite well (not battery) and offers a feature not often found in WiFi intercoms – a door release contact for remote opening of electronic locks on gates and doors. The same system also has WiFi touch screen monitors and we have found this system works best with a mesh WiFi system.  Usually the door station would be installed at a front door rather than at a gate due to WiFi system coverage.  This system can also provide cloud based calls to mobile and the cost of the mobile App licence is free if you purchase the door station and monitor.  Please see below.