CalypsoBTS with recent OsmoBTS in 2021?

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Hello,

I'm trying to run CalypsoBTS as described here:
https://osmocom.org/projects/baseband/wiki/CalypsoBTS

I'm using a single Motorola C123 phone and in my openbsc.conf, i have
only one CCCH+SDCCH4 channel on timeslot 0:

   timeslot 0
    phys_chan_config CCCH+SDCCH4
    hopping enabled 0
    
I'm using the fixeria/trx branch with recent OsmoBTS.

First, i load the trx firmware on the phone, and then i start the
transceiver host app to sync with a known ARFCN. The syncing goes
without any issues.

Then, i start OpenBSC through OsmoNITB like that:

osmo-nitb -c ~/.osmocom/openbsc.cfg -l ~/.osmocom/hlr.sqlite3 -P -C
--debug=DRLL:DCC:DMM:DRR:DRSL:DNM
--yes-i-really-want-to-run-prehistoric-software

And OsmoBTS:

osmo-bts-trx -c ~/.osmocom/osmo-bts.cfg

OsmoBTS fails almost instantly with:

<0012> input/ipaccess.c:898 received ID_GET for unit ID 1801/0/0
<000b> trx_if.c:701 phy0.0: Response message 'RSP ERR 1 ' does not
match command message 'CMD RFMUTE 1' <000b> trx_if.c:645 phy0.0:
transceiver rejected TRX command with response: 'ERR 1' <0001>
oml.c:221 (bts=0,trx=0): O&M Get Attributes [0], Manufacturer Dependent
State is unsupported by TRX. <000b> trx_if.c:134 phy0.0: Ignoring CLOCK
IND 2061832, TRX not yet powered on

The last message repeats until i terminate the application.

On the OsmoNITB side, i get:

<0005> abis_nm.c:550 OC=BTS(01) INST=(00,ff,ff) Get Attributes Response
for BTS0 <0005> abis_nm.c:463 BTS0 Get Attributes Response Info: 72
bytes total with 0 unreported attributes <0005> abis_nm.c:497 BTS0 Get
Attributes Response: reported unexpectedly long (3 bytes) feature
vector - most likely it was compiled against newer BSC headers.
Consider upgrading your BSC to later version. <0005> abis_nm.c:507 BTS0
feature 'Frequency Hopping' reported via OML does not match statically
set feature: 1 != 0. Please fix. <0005> abis_nm.c:507 BTS0 feature
'Multi-TSC' reported via OML does not match statically set feature:
1 != 0. Please fix. <0005> abis_nm.c:507 BTS0 feature 'OML Alerts'
reported via OML does not match statically set feature: 1 != 0. Please
fix. <0005> abis_nm.c:507 BTS0 feature 'CBCH' reported via OML does not
match statically set feature: 1 != 0. Please fix. <0005> abis_nm.c:577
BTS0: failed to parse SW-Config part of Get Attribute Response Info:
Invalid argument <0005> abis_nm.c:550 OC=BASEBAND-TRANSCEIVER(04)
INST=(00,00,ff) Get Attributes Response for BTS0 <0005> abis_nm.c:463
BTS0 Get Attributes Response Info: 34 bytes total with 1 unreported
attributes <0005> abis_nm.c:468 BTS0 Attribute Manufacturer Dependent
State is unreported <0005> abis_nm.c:577 BTS0: failed to parse
SW-Config part of Get Attribute Response Info: Invalid argument <0005>
abis_nm.c:771 OC=SITE-MANAGER(00) INST=(ff,ff,ff) Opstart ACK <0005>
abis_nm.c:381 OC=SITE-MANAGER(00) INST=(ff,ff,ff) STATE CHG:
OP_STATE=Enabled AVAIL=OK(ff) ADM=Locked <0005> abis_nm.c:1938
OC=SITE-MANAGER(00) INST=(ff,ff,ff) Sending OPSTART <0005>
abis_nm.c:771 OC=SITE-MANAGER(00) INST=(ff,ff,ff) Opstart ACK


And on the transceiver side, between the successful CLK Indication
messages, i get:

<0011> trx.c:509 [!] No handlers found for command 'RFMUTE'. Empty
response <0011> trx.c:226 TRX Control send: |RSP ERR 1 |


Is this issue due to the unimplemented in the transceiver command
"RFMUTE" or what really fails is:

<0005> abis_nm.c:577 BTS0: failed to parse SW-Config part of Get
Attribute Response Info: Invalid argument 

?

I also tried using components from their circa-2017-2018 revisions but
there are so many changes in core Osmocom libraries that they always
fail to compile and fixing them is hardly worth it, given the amount of
work it is.

I know OsmoNITB is abandoned since 2017, but currently this is the only
way for a beginner to experiment with BTS based on cheap Calypso
phones, as it is not implemented in the new Oscomcom stack.