Abis TCH UL captures from Nokia InSite¶

There is a Nokia InSite BTS at Themyscira HQ, connected to a driving setup that consists of an icE1usb adapter and an RPi5 host. We have a setup whereby we can make test calls with only one MS (no second phone or other MS is needed), we feed a stream of dummy and benign TRAU-DL frames into Abis DL to keep the BTS and the MS happy, and we can capture everything the BTS puts out on Abis in TCH UL direction.

TCH/F speech calls¶

So far we have tested FRv1 and EFR speech calls with DTXu enabled. (Configuring dtx uplink in OsmoBSC produces a vty warning, but the setting does get passed to the BTS and the MS, and it does take effect on subsequent test calls.) All of the following captures are raw octet streams from E1 timeslot 2 on Abis; in each case the active call was on 16 kbit/s subslot 2 out of the full E1 ts. Here are the captures:

• efr-dtx.bin: the codec was EFR, I alternated between speaking and silence during the test call, but did not press any DTMF keys.
• efr-dtx-dtmf.bin: the codec was EFR, I didn't speak this time, but I pressed DTMF keys to produce some FACCH activity during DTXu pauses.
• fr1-dtx.bin: the codec was FRv1, I alternated between speaking and silence, no DTMF.