fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/32793 )

Change subject: BTS_Tests: f_rtpem_activate(): pad speech frames with '01010101'B ......................................................................

BTS_Tests: f_rtpem_activate(): pad speech frames with '01010101'B

Since recently [1], osmo-bts started to preen incoming FR and EFR RTP frames for SID errors. In other words, if an incoming frame is a SID frame, osmo-bts may modify some bits causing a mismatch on our side.

Use '01010101'B as the padding pattern to prevent pseudo-random TCH frames being treated as SID and modified by osmo-bts.

Change-Id: Ib42b783574caf5cbaf64b2eb5dd1d2b2a6637c2f Related: [1] osmo-bts.git I89df2f12c49dd5378667cf149d19bde654f80134 Related: OS#6039 --- M bts/BTS_Tests.ttcn 1 file changed, 22 insertions(+), 2 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/osmo-ttcn3-hacks refs/changes/93/32793/1

diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn index 909a331..cddb6e7 100644 --- a/bts/BTS_Tests.ttcn +++ b/bts/BTS_Tests.ttcn @@ -2635,8 +2635,10 @@ } }

- /* Pad the payload to conform the expected length */ - payload := f_pad_oct(hdr & payload, payload_len, '00'O); + /* Pad the payload to conform the expected length. Use '01010101'B as + * padding pattern to ensure the resulting payload is *not* a SID frame, + * which may be corrected by the BTS causing mismatch on our side. */ + payload := f_pad_oct(hdr & payload, payload_len, '55'O); cfg.tx_payloads[0].fixed_payload := payload; f_rtpem_configure(RTPEM_CTRL, cfg);