Uber is testing adding train and coach travel to its app in the UK so customers can book longer distance ground travel via a fully integrated tie-up with Berlin-based multimodal travel platform, Omio.

The latter has built up its own consumer facing apps for booking intercity and international travel, across a wide variety of supported transport options, over almost a decade of operations. But, in recent years, it's been ploughing resource into building out a b2b line -- making its inventory available to partners via APIs so they can add transport booking options to their own apps and platforms.

Uber isn't the first such tie up for Omio, per founder and CEO Naren Shaam. But he tells TechCrunch it's the first partner to get full access to its ground transport inventory -- which covers more than 1,000 transportation providers across 37 countries at this point.

"Uber is the first partner that is both at this scale but also the first that gets access to our full ticketing API so you actually are, as a customer, able to do everything within the Uber app -- so it is the first with respect to this product that we're offering," he says.

Omio's earlier b2b partnerships include some transport providers themselves, such as UK-based LNER, as well as the travel search engine Kayak and smartphone maker Huawei, among others.

The ride hailing giant is also the biggest b2b partner Omio has signed up so far: Shaam says the tie-up will put its inventory in front of the circa 5 million+ customers Uber claims in the UK market.

And while Omio's own app includes non-ground transport options (like ferries and even flights) he says its platform remains strongest in inventory terms for booking train and coach/bus travel -- hence why it's starting there with Uber. Although Shaam hints there could be more to come. "This is the beginning of our partnership; it will expand -- beyond just geography," he suggests, noting that Omio's b2b partners can "pick and choose" from its full inventory range of supported transport models to offer their own customers.