(Pocket-lint) - The system that Apple and Google have jointly been working on to allow contact tracing via iPhone and Android devices will reportedly become available to developers from 28 April.

The system is designed to allow Google and Apple devices to be interoperable, using Bluetooth Low Energy to detect when those devices are in close proximity of other devices and to be used as the foundation for contact tracing to help combat the spread of COVID-19.

"Tim Cook told me that a first version of the technology that Apple is preparing in partnership with Google will be available to developers on 28 April," said Thierry Breton, European commissioner for internal markets.

The story goes a lot further than just Apple and Google, however, and this doesn't mean that contact tracing apps will then be available to the general public. Instead, this is when developers will be able to work with the tools that Google and Apple are making available, which will feed into different national apps for contact tracing, for example.

Those tools are designed to allow access to devices in ways that otherwise wouldn't be available, but that comes with restrictions on both sides. The EU has outlined its own guidance for privacy within contact tracing apps, while Google and Apple want to ensure that their own privacy conditions are met.

One of the stumbling blocks is potentially what you will and won't be able to do with the iPhone. Apple doesn't allow third-party apps access to Bluetooth when they're not running. That's designed as a security measure, but it would potentially mean that some contract tracing apps wouldn't work in the background on the iPhone, rendering them a little useless - and wiping out about 50 per cent of the potential userbase in most European countries.

One such example is the French app StopCovid which is in development and currently not planning on using he Apple-Google framework. This has led to a spat between French authorities and Apple, with the French wanting Apple to relax its systems to support such functionality - and something that Breton is pushing with Apple. 

"It is the responsibility of companies like Apple to do everything possible to develop appropriate technical solutions so that national applications work," said Breton. The UK's app in development by NHSX might find itself in the same position, wanting access to iPhone functions that aren't normally permitted, in the first instance at least.

This isn't the first time that governments have come up against Apple's security restrictions: the UK Government wanted Apple to allow it access to the iPhone's NFC system for its EU Exit ID Document Check app and that, reportedly, took a lot of negotiation.

One other issue is how authorities might want to use the data: some health agencies might want access to the data to inform their own infection monitoring, but this state-level data gathering raises huge privacy concerns from many angles.

On the flip side of that argument is Google: with the amount of data that Google could potentially have as its disposal, there's likely to be concern that it would then be able to create COVID-19 infection maps outside of national government controls, which is probably why the EU is keen to push it's own limitations on how this data can be used.

The most important thing is that there's willing on all parts to make a system that works and many of the pieces falling into place. With Apple and Google dominating the smartphone space and providing the tools, national contact tracing apps in development and a lot of people engaged with the process, many of these barriers will be overcome and, ultimately, form a part in easing the lockdown that much of the world currently finds itself under.

Writing by Chris Hall.