HTC has stopped offering its phones for sale in the UK while it is involved in an intellectual property dispute.
The Taiwanese company's online store currently lists all of its models as "out of stock" despite the fact they remain available in other nations.
HTC has been involved in a long-running dispute with research and development company Ipcom over a wireless technology developed for car phones.
To resolve it, HTC agreed to sell only mobiles with a workaround in the UK.
However, Munich-based Ipcom has alleged it carried out tests earlier this year that showed no workaround had been implemented.
It said HTC had failed to "play by the rules" and had displayed "disregard for the law by contravening a UK court ruling".
An HTC spokeswoman said: "As a leading innovator, HTC takes intellectual property issues very seriously.
"We are proactively investigating an infringement claim by a third party with respect to a single handset model."
HTC was the first manufacturer to sell an Android handset, in 2008. A decade later, it sold part of its smartphone division to Google.
Although it stayed in the business since - most notably launching a crypto-currency-focused model - it has struggled.
In the UK, Carphone Warehouse, O2 and EE had already stopped selling its phones.
This had left it reliant on sales via its own site and Amazon, which is still listing HTC handsets for sale.
HTC also makes a 5G router and virtual reality headsets, which remain on sale.