diff --git a/src/storage.h b/src/storage.h
new file mode 100644
index 0000000..d128a34
--- /dev/null
+++ b/src/storage.h
@@ -0,0 +1,21 @@
+#pragma once
+#include <stdint.h>
+
+enum osmo_e1cap_capture_mode {
+	OSMO_E1CAP_MODE_RAW,
+	OSMO_E1CAP_MODE_HDLC,
+	OSMO_E1CAP_MODE_TRAU,
+	OSMO_E1CAP_MODE_PGSL,
+};
+
+/* header for each frame we store */
+struct osmo_e1cap_pkthdr {
+	struct timeval ts;
+	uint32_t len;
+	uint8_t line_nr;
+	uint8_t ts_nr;
+	uint8_t capture_mode;
+	uint8_t flags;
+} __attribute__((aligned));
+
+int e1frame_store(struct e1inp_ts *ts, struct msgb *msg, enum osmo_e1cap_capture_mode mode);