Google and Samsung have confirmed that there are volume issues with their flagship mobile phone the Galaxy Nexus.
It follows complaints on net forums about unexplained changes in volume.
The handset, the first to feature Google's operating system Android Ice Cream Sandwich, is currently available in the UK and is due to go on sale in the US in December.
Samsung said that it is aware of the problem and will offer a repair but did not say when.
"Regarding the Galaxy Nexus, we are aware of the volume issue and have developed a fix," Samsung said in a statement. "We will update devices as soon as possible."
Google issued an almost identical statement.
Posting on Google's Android user forum Damian M summed up the problem many seem to be experiencing: "Volume drops to nothing seemingly at random, volume rocker becomes unresponsive for a few seconds," he said.
Some users reported that the issues became worse when using the 2G network. Others complained that they were unable to rely on the device.
"Had this problem since buying the phone on the 17 Nov. Happened so far on 3G, wifi and using the sat nav. It also happened this morning again when my alarm went off," wrote one user nicknamed Stuartea.
"I was already awake and had not touched the phone yet, the alarm sounded for a second and then went silent. Thought that was weird so checked the phone and the volume was down. I can't trust the alarm to wake me up now for work!"
It is unclear at this stage whether the issues are caused by hardware or software faults.
The problem comes as Apple rushes to fix a bug in its new operating system iOS 5.
Users complain that iPhone batteries are running down too quickly.
An initial software patch issued by Apple to solve the problem has not appeared to have helped.
Apple and Samsung are engaged in a fierce rivalry for market share.
Research from Strategy Analytics suggested that Samsung had overtaken Apple to become the world's biggest shipper of smartphones between July and September.
The study said that the South Korean firm had shipped 27.8 million smartphones in the three-month period, compared with 17.1 million from Apple and 16.8 million from Nokia.
Meanwhile, Samsung and Apple remain locked in intellectual property disputes around the world. Both are trying to ban sales of each other's products.