working state up to location update and classmark inquiry

diff --git a/src/gsm_data.c b/src/gsm_data.c
index e5ba906..61f8682 100644
--- a/src/gsm_data.c
+++ b/src/gsm_data.c
@@ -76,6 +76,8 @@
 		}
 
 		bts->num_trx = 1;	/* FIXME */
+		bts->c0 = &bts->trx[0];
+		bts->c0->ts[0].pchan = GSM_PCHAN_CCCH_SDCCH4;
 	}
 	return net;
 }