The Nexus 4 is a hit. Ever since Google (NASDAQ:GOOGL) launched its new Android flagship, the LG-built smartphone has been rather hard to come by. Even now, Google Play lists it as sold out domestically for both the 8 GB ($299) model and 16 GB ($349) model. That about describes demand for the device ever since it launched back in November.

The tricky bit is that Google doesn't disclose unit sales figures in general, so it's unclear how many units have actually moved. Well, some Android enthusiasts have tried to figure out production volume information based on serial numbers found on Nexus 4 boxes. Through some clever detective work using IMEI numbers printed on every mobile phone, they've been able to decode when and where their gadgets were produced, along with which unit it was numerically.

These Android loyalists estimate that there were approximately 70,000 units made in October, 90,000 in November, and 210,000 in December. Assuming the methodology is sound, we're talking about approximately 370,000 units produced in the fourth quarter. Of course, this is far from exact, but at the same time it could give investors an estimate of how many Nexus 4 units have sold so far.

That total is pretty light, and indicates that LG may have underestimated demand for the device and now needs to ramp up production. Nexus devices garner considerable interest, and I wouldn't be surprised if the Nexus 4 is selling better than LG's Optimus G (which the Nexus 4 is based on). For comparison, Samsung sold 30 million Galaxy S III units between May and November and 5 million Galaxy Note II units within its first two months.

T-Mobile is the only official carrier partner in the U.S. for the Nexus 4, and is supposedly receiving more inventory this month at its retail locations. For Android users, those units can't arrive soon enough.