1 million.

The number of HTC G1 sold in U.S.A by T-Mobile.

Source [In French]

Yet it is equipped with Android, an OS that HTC's competitors can also install on their smartphones.

And this Android, except for some drivers and 4 applications softwares, are FOSS.

These 4 applications softwares proprietary are:
- gMail --> replaceable by a FOSS e-mail client.
- gTalk --> replaceable by a FOSS IM Client.
- Google Map --> require much work, but replaceable by a FOSS Map Software.
- Adroid Market --> replaceable by a package manager (ex: PackageKit) to provide FOSS softwares.

So we can say that the HTC G1 was sold with an OS almost pure FOSS to 1 million copies.

There are exist even "100% FOSS version" of Android.

If HTC can it, Nokia can it.

PS: Some people ask for an example with numbers, it is.