diff --git a/src/isdnsync.c b/src/isdnsync.c
new file mode 100644
index 0000000..d8819ac
--- /dev/null
+++ b/src/isdnsync.c
@@ -0,0 +1,192 @@
+/* isdnsync.c
+ *
+ * Author       Andreas Eversberg <jolly@eversberg.eu>
+ *
+ * All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include "mISDNif.h"
+#define MISDN_OLD_AF_COMPATIBILITY
+#define AF_COMPATIBILITY_FUNC
+#include "compat_af_isdn.h"
+
+int card = 0;
+int sock = -1;
+
+int mISDN_open(void)
+{
+	int			fd, ret;
+	struct mISDN_devinfo	devinfo;
+	struct sockaddr_mISDN	l2addr;
+
+	fd = socket(PF_ISDN, SOCK_RAW, ISDN_P_BASE);
+	if (fd < 0) {
+		fprintf(stderr, "could not open socket (%s)\n", strerror(errno));
+		return fd;
+	}
+	devinfo.id = card;
+	ret = ioctl(fd, IMGETDEVINFO, &devinfo);
+	if (ret < 0) {
+		fprintf(stderr,"could not send IOCTL IMGETCOUNT (%s)\n", strerror(errno));
+		close(fd);
+		return ret;
+	}
+	close(fd);
+	if (!(devinfo.Dprotocols & (1 << ISDN_P_TE_S0))
+	 && !(devinfo.Dprotocols & (1 << ISDN_P_TE_E1))) {
+		fprintf(stderr,"Interface does not support TE mode (%s)\n", strerror(errno));
+		close(fd);
+		return ret;
+	}
+	fd = socket(PF_ISDN, SOCK_DGRAM, ISDN_P_LAPD_TE);
+	if (fd < 0) {
+		fprintf(stderr,"could not open ISDN_P_LAPD_TE socket (%s)\n", strerror(errno));
+		return fd;
+	}
+	l2addr.family = AF_ISDN;
+	l2addr.dev = card;
+	l2addr.channel = 0;
+	l2addr.sapi = 0;
+	l2addr.tei = 0;
+	ret = bind(fd, (struct sockaddr *)&l2addr, sizeof(l2addr));
+	if (ret < 0) {
+		fprintf(stderr,"could not bind socket for card %d (%s)\n", card, strerror(errno));
+		close(fd);
+		return ret;
+	}
+	sock = fd;
+
+	return sock;
+}
+
+
+void mISDN_handle(void)
+{
+	int ret;
+	fd_set rfd;
+	struct timeval tv;
+	struct sockaddr_mISDN addr;
+	socklen_t alen;
+	unsigned char buffer[2048];
+	struct mISDNhead *hh = (struct mISDNhead *)buffer;
+	int l1 = 0, l2 = 0, tei = 0;
+
+	while(1) {
+again:
+		FD_ZERO(&rfd);
+		FD_SET(sock, &rfd);
+		tv.tv_sec = 2;
+		tv.tv_usec = 0;
+		ret = select(sock+1, &rfd, NULL, NULL, &tv);
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			fprintf(stderr, "%s aborted: %s\n", __FUNCTION__, strerror(errno));
+			break;
+		}
+		if (FD_ISSET(sock, &rfd)) {
+			alen = sizeof(addr);
+			ret = recvfrom(sock, buffer, sizeof(buffer), 0, (struct sockaddr *) &addr, &alen);
+			if (ret < 0) {
+				fprintf(stderr, "%s read socket error %s\n", __FUNCTION__, strerror(errno));
+			} else if (ret < MISDN_HEADER_LEN) {
+					fprintf(stderr, "%s read socket shor frame\n", __FUNCTION__);
+			} else {
+				switch(hh->prim) {
+					case MPH_ACTIVATE_IND:
+					case PH_ACTIVATE_IND:
+						if (!l1) {
+							printf("PH_ACTIVATE\n");
+							printf("*** Sync available from interface :-)\n");
+							l1 = 1;
+						}
+						goto again;
+					break;
+					case MPH_DEACTIVATE_IND:
+					case PH_DEACTIVATE_IND:
+						if (l1) {
+							printf("PH_DEACTIVATE\n");
+							printf("*** Lost sync on interface        :-(\n");
+							l1 = 0;
+						}
+						goto again;
+					break;
+					case DL_ESTABLISH_IND:
+					case DL_ESTABLISH_CNF:
+						printf("DL_ESTABLISH\n");
+						l2 = 1;
+						goto again;
+					break;
+					case DL_RELEASE_IND:
+					case DL_RELEASE_CNF:
+						printf("DL_RELEASE\n");
+						l2 = 0;
+						goto again;
+					break;
+					case DL_INFORMATION_IND:
+						printf("DL_INFORMATION (tei %d sapi %d)\n", addr.tei, addr.sapi);
+						tei = 1;
+					break;
+					default:
+//						printf("prim %x\n", hh->prim);
+						goto again;
+				}
+			}
+		}
+		if (tei && !l2) {
+			hh->prim = DL_ESTABLISH_REQ;
+			printf("-> activating layer 2\n");
+			sendto(sock, buffer, MISDN_HEADER_LEN, 0, (struct sockaddr *) &addr, alen);
+		}
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+
+	if (argc <= 1)
+	{
+		printf("Usage: %s <card>\n\n", argv[0]);
+		printf("Opens given card number in TE-mode PTP and tries to keep layer 2 established.\n");
+		printf("This keeps layer 1 activated to retrieve a steady sync signal from network.\n");
+		return(0);
+	}
+
+	card = atoi(argv[1]);
+
+	init_af_isdn();
+
+	if ((ret = mISDN_open() < 0))
+		return(ret);
+
+	mISDN_handle();
+
+	close(sock);
+
+	return 0;
+}