preliminary ip.access BTS support, as of now only OML singalling works

diff --git a/src/e1_config.c b/src/e1_config.c
index 250d6c2..9863c9e 100644
--- a/src/e1_config.c
+++ b/src/e1_config.c
@@ -66,3 +66,32 @@
 
 	return mi_setup(0, line, NULL);
 }
+
+/* do some compiled-in configuration for our BTS/E1 setup */
+int ia_config(struct gsm_bts *bts)
+{
+	struct e1inp_line *line;
+	struct e1inp_ts *sign_ts;
+	struct e1inp_sign_link *oml_link, *rsl_link;
+
+	line = malloc(sizeof(*line));
+	if (!line)
+		return -ENOMEM;
+	memset(line, 0, sizeof(*line));
+
+	/* create E1 timeslots for signalling and TRAU frames */
+	e1inp_ts_config(&line->ts[1-1], line, E1INP_TS_TYPE_SIGN);
+
+	/* create signalling links for TS1 */
+	sign_ts = &line->ts[1-1];
+	oml_link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_OML,
+					  bts->c0, 0, 0xff);
+	rsl_link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_RSL,
+					  bts->c0, 0, 0);
+
+	/* create back-links from bts/trx */
+	bts->oml_link = oml_link;
+	bts->c0->rsl_link = rsl_link;
+
+	return ipaccess_setup(line);
+}