Hi Andreas, I'm having some problems while bootstrapping RBS2308 with the existing code. I think it is related to LAPD sequence number checkings: lapd.c:595 TX: 02 01 02 00 0c 11 01 80 1e 02 27 17 59 06 0 00 00 00 00 00 00 00 00 00 00 00 00 ff e5 04 00 dahdi.c:248 dahdi TX (TS=1): 37 bytes lapd_core.c:1832 msg-len 31 sent 31 left 0 N201 260 t byte 0c lapd.c:345 RX: 02 01 01 04 lapd_core.c:1256 RR received in state LAPD_STATE_MF_EST lapd_core.c:739 ack frame 1 lapd_core.c:216 stop T200 lapd_core.c:208 start T203 lapd_core.c:1780 lapd_send_i() called from line 1294 lapd.c:345 RX: 00 01 02 04 10 1c 1a 02 62 11 1c 11 01 80 lapd_core.c:1463 I received in state LAPD_STATE_MF_EST lapd_core.c:1512 N(S) sequence error: N(S)=1, V(R)=0 ^^^^^^^^^^^^^^ It seems to me that the BSC transmits data while something is still coming from the BTS. Then, BSC's LAPD code silently drops the message (without rejection). Just a bit later the BSC gets a rejection from BTS's RSL layer. lapd.c:595 TX: 00 01 09 00 dahdi.c:248 dahdi TX (TS=1): 6 bytes lapd_core.c:224 stop T203 lapd_core.c:208 start T203 lapd_core.c:1780 lapd_send_i() called from line 1538 lapd.c:345 RX: 00 01 00 04 10 1c 1a 02 62 11 1c 11 01 80 lapd_core.c:1463 I received in state LAPD_STATE_MF_EST lapd_core.c:1546 incrementing V(R) to 1 lapd_core.c:224 stop T203 lapd_core.c:208 start T203 lapd_core.c:1555 message in single I frame abis_rsl.c:1128 (bts=0,trx=0) ERROR REPORT CAUSE=0x62(Message Sequence Error) So the bootstrapping process never ends and the BTS never comes up. Let me know if you can provide any clue to resolve this issue. Thanks!