T-Mobile 4G LTE CellSpot¶

Any information that is and will be posted here is based on reverse engineering, without support from T-Mobile. Use at your own risk.

The T-Mobile and Nokia branded version has been labled as the 4G LTE CellSpot V2 with the model "SS2FII Femtocell Multi-band SOHO". The Nokia-only branded version (pictured by the FCC) has been labeled with the model name "SOHO Small Cell V2 B2/B4"

The device does not seem to support GSM, only UMTS and LTE. According to pictures of the internals by the FCC, the SoC is a Qualcomm FSM9955: https://cdn-0.fccid.io/png.php?id=3432311&page=5

This SoC incorporates a DSP by Qualcomm from the Hexagon series.

There is a Linux kernel for the FSM99xx series released, made with Yocto
https://github.com/ipaccess/fsm99xx-kernel-sources

According to the generic device tree include header, the FSM9900 series seems to be based on the 2012-era ARMv7 Qualcomm Krait cores:
https://github.com/ipaccess/fsm99xx-kernel-sources/blob/master/arch/arm/boot/dts/qcom/fsm9900.dtsi

According to a Reddit post the FSM9955 also uses a Krait core, but I don't have the kernel sources to confirm this: https://old.reddit.com/r/tmobile/comments/7ii5jm/4g_lte_cellspot_v2_virtual_teardown/

Maybe request more recent kernel sources from T-Mobile or Nokia.

• Paper about the Haxagon architecture: http://pages.cs.wisc.edu/~danav/pubs/qcom/hexagon_micro2014_v6.pdf
• FCC page: https://fccid.io/H8NSS2FII