Initial commit

1 files changed, 849 insertions, 0 deletions

diff --git a/src/telephone/telephone.c b/src/telephone/telephone.c
new file mode 100644
index 0000000..343efad
--- /dev/null
+++ b/src/telephone/telephone.c
@@ -0,0 +1,849 @@
+/* console handling
+ *
+ * (C) 2020 by 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <stddef.h>
+#include "../libdebug/debug.h"
+#include "../libsample/sample.h"
+#include "../libg711/g711.h"
+#include "../libsound/sound.h"
+#include "telephone.h"
+#include "../libosmocc/helper.h"
+
+static struct osmo_cc_helper_audio_codecs codecs[] = {
+	{ "PCMA", 8000, 1, g711_encode_alaw, g711_decode_alaw },
+	{ "PCMU", 8000, 1, g711_encode_ulaw, g711_decode_ulaw },
+	{ NULL, 0, 0, NULL, NULL},
+};
+
+const char *cause_name(int cause)
+{
+	static char cause_str[16];
+
+	switch (cause) {
+	case OSMO_CC_ISDN_CAUSE_NORM_CALL_CLEAR:
+		return "hangup";
+	case OSMO_CC_ISDN_CAUSE_USER_BUSY:
+		return "busy";
+	case OSMO_CC_ISDN_CAUSE_USER_ALERTING_NA:
+		return "no-answer";
+	case OSMO_CC_ISDN_CAUSE_DEST_OOO:
+	case OSMO_CC_ISDN_CAUSE_NETWORK_OOO:
+		return "out-of-order";
+	case OSMO_CC_ISDN_CAUSE_INV_NR_FORMAT:
+		return "invalid-number";
+	case OSMO_CC_ISDN_CAUSE_NO_CIRCUIT_CHAN:
+		return "no-channel";
+	case OSMO_CC_ISDN_CAUSE_TEMP_FAILURE:
+		return "link-failure";
+	case OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL:
+		return "resource-unavail";
+	default:
+		sprintf(cause_str, "cause=%d", cause);
+		return cause_str;
+	}
+
+}
+
+static char ui_text[256];
+static char ui_clear[256];
+static int ui_autoalert;
+static int ui_autoanswer;
+static int ui_len = 0;
+#define UI_MAX_DIGITS 33
+static char ui_remote_id[256] = ""; /* what we dial or who called us */
+static char ui_remote_dialing[256] = ""; /* what remote called us with */
+static char ui_local_id[256] = ""; /* our ID */
+static const char ui_digits[] = "0123456789*#ABCDE";
+static uint8_t ui_cause = 0;
+
+static void append_string(char *string, size_t size, char c)
+{
+	size_t len = strlen(string);
+	int i;
+
+	/* string full */
+	if (len == size - 1)
+		return;
+
+	for (i = 0; i < (int)strlen(ui_digits); i++) {
+		if (c == ui_digits[i]) {
+			string[len] = c;
+			string[len + 1] = '\0';
+			break;
+		}
+	}
+}
+
+/*
+ * Endpoint instance
+ */
+
+/* create interface instance */
+telephone_t *telephone_create(void)
+{
+	telephone_t *telephone_ep;
+
+	telephone_ep = calloc(1, sizeof(*telephone_ep));
+	if (!telephone_ep) {
+		PDEBUG(DTEL, DEBUG_ERROR, "No memory!\n");
+		abort();
+	}
+
+	PDEBUG(DTEL, DEBUG_DEBUG, "Telephone instance created\n");
+
+	return telephone_ep;
+}
+
+static void telephone_close(telephone_t *telephone_ep);
+static void call_destroy(call_t *call);
+
+/* destroy interface instance and free all resource */
+void telephone_destroy(telephone_t *telephone_ep)
+{
+	/* remove stack instance */
+	telephone_close(telephone_ep);
+
+	/* destroy all calls */
+	while (telephone_ep->call_list)
+		call_destroy(telephone_ep->call_list);
+
+	free((char *)telephone_ep->name);
+
+	free(telephone_ep);
+
+	PDEBUG(DTEL, DEBUG_DEBUG, "Telephone instance destroyed\n");
+}
+
+/* initialization and configuration of interface instance */
+int telephone_init(telephone_t *telephone_ep, const char *name, const char *callerid, uint8_t serving_location, int early_audio, const char *audiodev, int samplerate, int __attribute__((unused)) latspl)
+{
+	telephone_ep->name = strdup(name);
+	telephone_ep->serving_location = serving_location;
+	telephone_ep->early_audio = early_audio;
+	telephone_ep->samplerate = samplerate;
+	telephone_ep->latspl = latspl;
+	telephone_ep->loopback = 0;
+	strcpy(ui_local_id, callerid);
+
+	if (audiodev) {
+#ifdef HAVE_ALSA
+		/* open sound device for call control */
+		/* use factor 1.4 of speech level for complete range of sound card */
+		telephone_ep->sound = sound_open(audiodev, NULL, NULL, NULL, 1, 0.0, samplerate, latspl, 1 / (SPEECH_LEVEL * 0.7079), 4000.0, 2.0);
+		if (!telephone_ep->sound) {
+			PDEBUG(DTEL, DEBUG_ERROR, "No sound device!\n");
+			return -EIO;
+		}
+		sound_start(telephone_ep->sound);
+#else
+		PDEBUG(DTEL, DEBUG_ERROR, "No sound card support compiled in!\n");
+		return -ENOTSUP;
+#endif
+	}
+
+	return 0;
+}
+
+static void telephone_close(telephone_t *telephone_ep)
+{
+	if (telephone_ep->sound) {
+		sound_close(telephone_ep->sound);
+		telephone_ep->sound = NULL;
+	}
+}
+
+/*
+ * call instance
+ */
+
+static const char *call_state_name[] = {
+	"on hook",
+	"incoming setup",
+	"outgoing setup",
+	"incoming overlap",
+	"outgoing overlap",
+	"incoming proceeding",
+	"outgoing proceeding",
+	"incoming alerting",
+	"outgoing alerting",
+	"connected",
+	"incoming disconect",
+	"outgoing disconect",
+};
+
+static void call_new_state(call_t *call, enum call_state state)
+{
+	PDEBUG(DTEL, DEBUG_DEBUG, "Call state '%s' -> '%s'\n", call_state_name[call->state], call_state_name[state]);
+	call->state = state;
+}
+
+static call_t *call_create(telephone_t *telephone_ep)
+{
+	call_t *call, **call_p;
+	int rc;
+
+	call = calloc(1, sizeof(*call));
+	if (!call) {
+		PDEBUG(DTEL, DEBUG_ERROR, "No memory!\n");
+		abort();
+	}
+
+	call_p = &telephone_ep->call_list;
+	while (*call_p)
+		call_p = &((*call_p)->next);
+	*call_p = call;
+
+	call->telephone_ep = telephone_ep;
+
+	/* init sample rate conversion */ 
+	rc = init_samplerate(&call->srstate, 8000.0, (double)telephone_ep->samplerate, 3300.0);
+	if (rc < 0)
+		abort();
+
+	/* allocate jitter buffer */
+	rc = jitter_create(&call->dejitter, telephone_ep->samplerate / 10); // FIXME: size
+	if (rc < 0)
+		abort();
+
+	PDEBUG(DTEL, DEBUG_DEBUG, "Created new call instance\n");
+
+	return call;
+}
+
+static void call_destroy(call_t *call)
+{
+	call_t **call_p;
+
+	/* free sdp */
+	free((char *)call->sdp);
+
+	/* free jitter buffer */
+	jitter_destroy(&call->dejitter);
+
+	/* free session description */
+	if (call->cc_session)
+		osmo_cc_free_session(call->cc_session);
+
+	/* detach */
+	call_p = &call->telephone_ep->call_list;
+	while (*call_p) {
+		if (*call_p == call)
+			break;
+		call_p = &((*call_p)->next);
+	}
+	*call_p = call->next;
+
+	free(call);
+
+	PDEBUG(DTEL, DEBUG_DEBUG, "destroyed call instance\n");
+}
+
+/*
+ * audio handling
+ */
+
+/* take audio from CC and store in jitter buffer */
+void down_audio(struct osmo_cc_session_codec *codec, uint16_t __attribute__((unused)) sequence_number, uint32_t __attribute__((unused)) timestamp, uint8_t *data, int len)
+{
+	call_t *call = codec->media->session->priv;
+	int count = len / 2;
+	sample_t samples[count];
+
+	if (call->telephone_ep->loopback != 3) {
+		sample_t up[(int)((double)count * call->srstate.factor + 0.5) + 10];
+		int16_to_samples(samples, (int16_t *)data, count);
+		count = samplerate_upsample(&call->srstate, samples, count, up);
+		jitter_save(&call->dejitter, up, count);
+	}
+}
+
+void alsa_work(telephone_t *telephone_ep)
+{
+	if (!telephone_ep->sound)
+		return;
+
+#ifdef HAVE_ALSA
+	/* handle audio, if sound device is used */
+	call_t *call;
+	sample_t samples[telephone_ep->latspl + 10], *samples_list[1];
+	uint8_t *power_list[1];
+	int count;
+	int rc;
+
+	/* hunt for call */
+	for (call = telephone_ep->call_list; call; call = call->next)
+		break; // just any call
+
+	count = sound_get_tosend(telephone_ep->sound, telephone_ep->latspl);
+	if (count < 0) {
+		PDEBUG(DTEL, DEBUG_ERROR, "Failed to get samples in buffer (rc = %d)!\n", count);
+		if (count == -EPIPE)
+			PDEBUG(DTEL, DEBUG_ERROR, "Trying to recover.\n");
+		return;
+	}
+	if (count > 0) {
+		if (call)
+			jitter_load(&call->dejitter, samples, count);
+		else
+			memset(samples, 0, sizeof(*samples) * count);
+		samples_list[0] = samples;
+		power_list[0] = NULL;
+		rc = sound_write(telephone_ep->sound, samples_list, power_list, count, NULL, NULL, 1);
+		if (rc < 0) {
+			PDEBUG(DTEL, DEBUG_ERROR, "Failed to write TX data to sound device (rc = %d)\n", rc);
+			if (rc == -EPIPE)
+				PDEBUG(DTEL, DEBUG_ERROR, "Trying to recover.\n");
+			return;
+		}
+	}
+	samples_list[0] = samples;
+	count = sound_read(telephone_ep->sound, samples_list, telephone_ep->latspl, 1, NULL);
+	if (count < 0) {
+		PDEBUG(DTEL, DEBUG_ERROR, "Failed to read from sound device (rc = %d)!\n", count);
+		if (count == -EPIPE)
+			PDEBUG(DTEL, DEBUG_ERROR, "Trying to recover.\n");
+		return;
+	}
+	if (call && count) {
+		int i;
+
+		if (telephone_ep->loopback == 3)
+			jitter_save(&call->dejitter, samples, count);
+		count = samplerate_downsample(&call->srstate, samples, count);
+		/* put samples into ring buffer */
+		for (i = 0; i < count; i++) {
+			call->tx_buffer[call->tx_buffer_pos] = samples[i];
+			/* if ring buffer wrapps, deliver data down to call process */
+			if (++call->tx_buffer_pos == 160) {
+				call->tx_buffer_pos = 0;
+				/* only if we have a call */
+				if (call->cc_callref && call->codec) {
+					int16_t data[160];
+					samples_to_int16(data, call->tx_buffer, 160);
+					osmo_cc_rtp_send(call->codec, (uint8_t *)data, 160 * 2, 1, 160);
+				}
+			}
+		}
+	}
+
+//printf("%p, %p\n", call, call ? call->codec : NULL);
+//	if (call && call->codec)
+//		while (osmo_cc_rtp_receive(call->codec->media) >= 0);
+#endif
+}
+
+void rtp_work(telephone_t *telephone_ep)
+{
+	call_t *call;
+
+	call = telephone_ep->call_list;
+	while (call) {
+		if (call->cc_session)
+			osmo_cc_session_handle(call->cc_session);
+		call = call->next;
+	}
+}
+
+
+/*
+ * handle message from CC
+ */
+
+static void release_reject_ind(call_t *call, uint8_t msg_type, uint8_t isdn_cause)
+{
+	osmo_cc_msg_t *new_msg;
+
+	/* create osmo-cc message */
+	new_msg = osmo_cc_new_msg(msg_type);
+	/* cause */
+	osmo_cc_add_ie_cause(new_msg, call->telephone_ep->serving_location, isdn_cause, 0, 0);
+	/* send message to osmo-cc */
+	osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, new_msg);
+	/* change state */
+	call_new_state(call, CALL_STATE_IDLE);
+	/* destroy call */
+	call_destroy(call);
+}
+
+void cc_message(osmo_cc_endpoint_t *ep, uint32_t callref, osmo_cc_msg_t *msg)
+{
+	telephone_t *telephone_ep = ep->priv;
+	call_t *call, *other;
+	osmo_cc_msg_t *new_msg;
+	uint8_t type, plan, present, screen;
+	char callerid[128], dialing[128];
+	uint8_t coding, location, progress, socket_cause;
+	uint16_t sip_cause;
+	int rc;
+	int i;
+
+	/* hunt for callref */
+	call = telephone_ep->call_list;
+	while (call) {
+		if (call->cc_callref == callref)
+			break;
+		call = call->next;
+	}
+
+	/* process SETUP */
+	if (!call) {
+		if (msg->type != OSMO_CC_MSG_SETUP_REQ) {
+			PDEBUG(DTEL, DEBUG_ERROR, "received message without call instance, please fix!\n");
+			goto done;
+		}
+		/* creating call instance */
+		call = call_create(telephone_ep);
+		if (!call) {
+			PDEBUG(DTEL, DEBUG_ERROR, "Cannot create calll instance.\n");
+			abort();
+		}
+		/* link with cc */
+		call->cc_callref = callref;
+	}
+
+	switch (msg->type) {
+	case OSMO_CC_MSG_SETUP_REQ: /* dial-out command received from epoint */
+		/* hunt for call */
+		for (other = telephone_ep->call_list; other; other = other->next) {
+			if (other != call)
+				break;
+		}
+		if (other) {
+			release_reject_ind(call, OSMO_CC_MSG_REJ_IND, OSMO_CC_ISDN_CAUSE_USER_BUSY);
+			break;
+		}
+		/* calling */
+		rc = osmo_cc_get_ie_calling(msg, 0, &type, &plan, &present, &screen, callerid, sizeof(callerid));
+		if (rc >= 0)
+			strncpy(ui_remote_id, callerid, sizeof(ui_remote_id) - 1);
+		/* called */
+		rc = osmo_cc_get_ie_called(msg, 0, &type, &plan, dialing, sizeof(dialing));
+		if (rc >= 0)
+			strncpy(ui_remote_dialing, dialing, sizeof(ui_remote_dialing) - 1);
+		PDEBUG(DTEL, DEBUG_INFO, "Incoming call from '%s' to '%s'\n", ui_remote_id, ui_remote_dialing);
+		/* sdp accept */
+		call->sdp = osmo_cc_helper_audio_accept(call, codecs, down_audio, msg, &call->cc_session, &call->codec, 0);
+		if (!call->sdp) {
+			release_reject_ind(call, OSMO_CC_MSG_REJ_IND, OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL);
+			break;
+		}
+		call->sdp = strdup(call->sdp);
+		/* change state */
+		call_new_state(call, CALL_STATE_IN_SETUP);
+		if (ui_autoanswer) {
+			/* create osmo-cc message */
+			new_msg = osmo_cc_new_msg(OSMO_CC_MSG_SETUP_CNF);
+			/* sdp */
+			osmo_cc_add_ie_sdp(new_msg, call->sdp);
+			free((char *)call->sdp);
+			call->sdp = NULL;
+			/* send message to osmo-cc */
+			osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, new_msg);
+			/* change state */
+			call_new_state(call, CALL_STATE_CONNECT);
+		} else
+		if (ui_autoalert) {
+			/* create osmo-cc message */
+			new_msg = osmo_cc_new_msg(OSMO_CC_MSG_ALERT_IND);
+			/* sdp */
+			osmo_cc_add_ie_sdp(new_msg, call->sdp);
+			free((char *)call->sdp);
+			call->sdp = NULL;
+			/* send message to osmo-cc */
+			osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, new_msg);
+			/* change state */
+			call_new_state(call, CALL_STATE_IN_ALERTING);
+		}
+		break;
+	case OSMO_CC_MSG_SETUP_ACK_REQ: /* more information is needed */
+		rc = osmo_cc_helper_audio_negotiate(msg, &call->cc_session, &call->codec);
+		if (rc < 0) {
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL);
+			break;
+		}
+		PDEBUG(DTEL, DEBUG_INFO, "Incoming call acknowledged\n");
+		/* change state */
+		call_new_state(call, CALL_STATE_OUT_OVERLAP);
+		break;
+	case OSMO_CC_MSG_PROC_REQ: /* call of endpoint is proceeding */
+		rc = osmo_cc_helper_audio_negotiate(msg, &call->cc_session, &call->codec);
+		if (rc < 0) {
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL);
+			break;
+		}
+		PDEBUG(DTEL, DEBUG_INFO, "Incoming call proceeding\n");
+		/* change state */
+		call_new_state(call, CALL_STATE_OUT_PROCEEDING);
+		break;
+	case OSMO_CC_MSG_ALERT_REQ: /* call of endpoint is ringing */
+		rc = osmo_cc_helper_audio_negotiate(msg, &call->cc_session, &call->codec);
+		if (rc < 0) {
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL);
+			break;
+		}
+		PDEBUG(DTEL, DEBUG_INFO, "Incoming call alerting\n");
+		/* change state */
+		call_new_state(call, CALL_STATE_OUT_ALERTING);
+		break;
+	case OSMO_CC_MSG_SETUP_RSP: /* call of endpoint is connected */
+		rc = osmo_cc_helper_audio_negotiate(msg, &call->cc_session, &call->codec);
+		if (rc < 0) {
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL);
+			break;
+		}
+		PDEBUG(DTEL, DEBUG_INFO, "Incoming call acknowledged\n");
+		/* create osmo-cc message */
+		new_msg = osmo_cc_new_msg(OSMO_CC_MSG_SETUP_COMP_IND);
+		/* send message to osmo-cc */
+		osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, new_msg);
+		/* change state */
+		call_new_state(call, CALL_STATE_CONNECT);
+		break;
+	case OSMO_CC_MSG_SETUP_COMP_REQ: /* call of endpoint is connected */
+		break;
+	case OSMO_CC_MSG_INFO_REQ: /* overlap dialing */
+		rc = osmo_cc_get_ie_called(msg, 0, &type, &plan, dialing, sizeof(dialing));
+		if (rc < 0)
+			dialing[0] = '\0';
+		PDEBUG(DTEL, DEBUG_INFO, "Incoming call received additional dialing '%s'\n", dialing);
+		for (i = 0; dialing[i]; i++) {
+			/* add to dial string */
+			append_string(ui_remote_dialing, sizeof(ui_remote_dialing), dialing[i]);
+		}
+		break;
+	case OSMO_CC_MSG_PROGRESS_REQ: /* progress */
+		rc = osmo_cc_helper_audio_negotiate(msg, &call->cc_session, &call->codec);
+		if (rc < 0) {
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL);
+			break;
+		}
+		PDEBUG(DTEL, DEBUG_INFO, "Incoming call received progress\n");
+		break;
+	case OSMO_CC_MSG_NOTIFY_REQ: /* display and notifications */
+		break;
+	case OSMO_CC_MSG_REJ_REQ: /* call has been rejected */
+		/* get cause */
+		rc = osmo_cc_get_ie_cause(msg, 0, &location, &ui_cause, &sip_cause, &socket_cause);
+		if (rc < 0)
+			ui_cause = OSMO_CC_ISDN_CAUSE_NORM_CALL_CLEAR;
+		else
+			PDEBUG(DTEL, DEBUG_INFO, "Incoming call rejected: ISDN cause = %d, SIP cause = %d, socket cause = %d\n", ui_cause, sip_cause, socket_cause);
+		/* change state */
+		call_new_state(call, CALL_STATE_IDLE);
+		/* destroy call */
+		call_destroy(call);
+		break;
+	case OSMO_CC_MSG_DISC_REQ: /* call has been disconnected */
+		rc = osmo_cc_helper_audio_negotiate(msg, &call->cc_session, &call->codec);
+		if (rc < 0) {
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, OSMO_CC_ISDN_CAUSE_RESOURCE_UNAVAIL);
+			break;
+		}
+		/* get cause */
+		rc = osmo_cc_get_ie_cause(msg, 0, &location, &ui_cause, &sip_cause, &socket_cause);
+		if (rc < 0)
+			ui_cause = OSMO_CC_ISDN_CAUSE_NORM_CALL_CLEAR;
+		else
+			PDEBUG(DTEL, DEBUG_INFO, "Disconnect by remote: ISDN cause = %d, SIP cause = %d, socket cause = %d\n", ui_cause, sip_cause, socket_cause);
+		/* change state */
+		call_new_state(call, CALL_STATE_IN_DISCONNECT);
+		/* progress indicator */
+		rc = osmo_cc_get_ie_progress(msg, 0, &coding, &location, &progress);
+		if (rc < 0 || coding != OSMO_CC_CODING_ITU_T || !(progress == 1 || progress == 8)) {
+			PDEBUG(DTEL, DEBUG_INFO, "no audio after disconnect, releasing!\n");
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, ui_cause);
+		}
+
+		break;
+	case OSMO_CC_MSG_REL_REQ: /* release call */
+		/* get cause */
+		rc = osmo_cc_get_ie_cause(msg, 0, &location, &ui_cause, &sip_cause, &socket_cause);
+		if (rc < 0)
+			ui_cause = OSMO_CC_ISDN_CAUSE_NORM_CALL_CLEAR;
+		else
+			PDEBUG(DTEL, DEBUG_INFO, "Disconnect by remote: ISDN cause = %d, SIP cause = %d, socket cause = %d\n", ui_cause, sip_cause, socket_cause);
+		/* create osmo-cc message */
+		new_msg = osmo_cc_new_msg(OSMO_CC_MSG_REL_CNF);
+		/* send message to osmo-cc */
+		osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, new_msg);
+		/* change state */
+		call_new_state(call, CALL_STATE_IDLE);
+		/* destroy call */
+		call_destroy(call);
+		break;
+	default:
+		PDEBUG(DTEL, DEBUG_ERROR, "received an unsupported CC message: %d\n", msg->type);
+	}
+
+done:
+	osmo_cc_free_msg(msg);
+}
+
+/*
+ * user interface
+ */
+
+
+static void _clear_ui_text(void)
+{
+	if (!ui_len)
+		return;
+
+	fwrite(ui_clear, ui_len, 1, stdout);
+	// note: fflused by user of this function
+	ui_len = 0;
+}
+
+static void _print_ui_text(void)
+{
+	if (!ui_len)
+		return;
+
+	printf("\033[1;37m");
+	fwrite(ui_text, ui_len, 1, stdout);
+	printf("\033[0;39m");
+}
+
+int ui_init(const char *remote_id, int autoalert, int autoanswer)
+{
+	clear_console_text = _clear_ui_text;
+	print_console_text = _print_ui_text;
+	ui_autoalert = autoalert;
+	ui_autoanswer = autoanswer;
+
+	strncpy(ui_remote_id, remote_id, sizeof(ui_remote_id) - 1);
+	ui_remote_id[sizeof(ui_remote_id) - 1] = '\0';
+
+	return 0;
+}
+
+int ui_work(telephone_t *telephone_ep, int c)
+{
+	int work = (c > 0) ? 1 : 0;
+	call_t *call;
+	osmo_cc_msg_t *msg;
+	char text[1024] = "";
+	char display[UI_MAX_DIGITS + 1];
+	int len;
+
+	/* hunt for call */
+	for (call = telephone_ep->call_list; call; call = call->next)
+		break; // just any call
+	if (!call) {
+		if (c > 0) {
+			append_string(ui_remote_id, sizeof(ui_remote_id), c);
+			if ((c == 8 || c == 127) && strlen(ui_remote_id))
+				ui_remote_id[strlen(ui_remote_id) - 1] = '\0';
+dial_after_hangup:
+			if (c == 'd') {
+				PDEBUG(DTEL, DEBUG_INFO, "Outgoing call from '%s' to '%s'\n", ui_local_id, ui_remote_id);
+				ui_remote_dialing[0] = '\0';
+				/* creating call instance */
+				call = call_create(telephone_ep);
+				if (!call) {
+					PDEBUG(DTEL, DEBUG_ERROR, "Cannot create calll instance.\n");
+					abort();
+				}
+
+				/* setup message */
+				msg = osmo_cc_new_msg(OSMO_CC_MSG_SETUP_IND);
+				/* network type */
+				osmo_cc_add_ie_calling_network(msg, OSMO_CC_NETWORK_ALSA_NONE, "");
+				/* calling number */
+				osmo_cc_add_ie_calling(msg, OSMO_CC_TYPE_UNKNOWN, OSMO_CC_PLAN_TELEPHONY, OSMO_CC_PRESENT_ALLOWED, OSMO_CC_SCREEN_USER_UNSCREENED, ui_local_id);
+				/* called number */
+				osmo_cc_add_ie_called(msg, OSMO_CC_TYPE_UNKNOWN, OSMO_CC_PLAN_TELEPHONY, ui_remote_id);
+				/* bearer capability */
+				osmo_cc_add_ie_bearer(msg, OSMO_CC_CODING_ITU_T, OSMO_CC_CAPABILITY_AUDIO, OSMO_CC_MODE_CIRCUIT);
+				/* sdp offer */
+				call->cc_session = osmo_cc_helper_audio_offer(call, codecs, down_audio, msg, 1);
+				if (!call->cc_session) {
+					PDEBUG(DTEL, DEBUG_NOTICE, "Failed to offer audio, call aborted.\n");
+					osmo_cc_free_msg(msg);
+					call_destroy(call);
+				} else {
+					/* create new call */
+					osmo_cc_call_t *cc_call = osmo_cc_call_new(&call->telephone_ep->cc_ep);
+					call->cc_callref = cc_call->callref;
+					/* send message to CC */
+					osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, msg);
+					/* change state */
+					call_new_state(call, CALL_STATE_OUT_SETUP);
+				}
+			}
+		}
+		memset(display, '.', UI_MAX_DIGITS);
+		memcpy(display, ui_remote_id, strlen(ui_remote_id));
+		display[UI_MAX_DIGITS] = '\0';
+		sprintf(text, "%s: %s (press digits 0..9 or d=dial)\r", call_state_name[(call) ? call->state : CALL_STATE_IDLE], display);
+		goto done;
+	}
+
+	if (c == 'h' || (c == 'd' && call->state == CALL_STATE_IN_DISCONNECT)) {
+		PDEBUG(DTEL, DEBUG_INFO, "Call hangup\n");
+		/* create osmo-cc message */
+		if (call->state == CALL_STATE_IN_SETUP)
+			release_reject_ind(call, OSMO_CC_MSG_REJ_IND, OSMO_CC_ISDN_CAUSE_NORM_CALL_CLEAR);
+		else
+			release_reject_ind(call, OSMO_CC_MSG_REL_IND, OSMO_CC_ISDN_CAUSE_NORM_CALL_CLEAR);
+		/* dial new number */
+		if (c == 'd') {
+			call = NULL;
+			goto dial_after_hangup;
+		}
+		goto done;
+	}
+	if (c == 'o' && call->state == CALL_STATE_IN_SETUP) {
+		PDEBUG(DTEL, DEBUG_INFO, "Acknowledge incoming call\n");
+		/* create osmo-cc message */
+		msg = osmo_cc_new_msg(OSMO_CC_MSG_SETUP_ACK_IND);
+		if (call->telephone_ep->early_audio && call->sdp) {
+			/* progress */
+			osmo_cc_add_ie_progress(msg, OSMO_CC_CODING_ITU_T, call->telephone_ep->serving_location, OSMO_CC_PROGRESS_INBAND_INFO_AVAILABLE);
+			/* sdp */
+			osmo_cc_add_ie_sdp(msg, call->sdp);
+			free((char *)call->sdp);
+			call->sdp = NULL;
+		}
+		/* send message to osmo-cc */
+		osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, msg);
+		/* change state */
+		call_new_state(call, CALL_STATE_IN_OVERLAP);
+	}
+	if (c == 'p' && (call->state == CALL_STATE_IN_SETUP || call->state == CALL_STATE_IN_OVERLAP)) {
+		PDEBUG(DTEL, DEBUG_INFO, "Proceeding incoming call\n");
+		/* create osmo-cc message */
+		msg = osmo_cc_new_msg(OSMO_CC_MSG_PROC_IND);
+		if (call->telephone_ep->early_audio && call->sdp) {
+			/* progress */
+			osmo_cc_add_ie_progress(msg, OSMO_CC_CODING_ITU_T, call->telephone_ep->serving_location, OSMO_CC_PROGRESS_INBAND_INFO_AVAILABLE);
+			/* sdp */
+			osmo_cc_add_ie_sdp(msg, call->sdp);
+			free((char *)call->sdp);
+			call->sdp = NULL;
+		}
+		/* send message to osmo-cc */
+		osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, msg);
+		/* change state */
+		call_new_state(call, CALL_STATE_IN_PROCEEDING);
+	}
+	if (c == 'a' && (call->state == CALL_STATE_IN_SETUP || call->state == CALL_STATE_IN_OVERLAP || call->state == CALL_STATE_IN_PROCEEDING)) {
+		PDEBUG(DTEL, DEBUG_INFO, "Alerting incoming call\n");
+		/* create osmo-cc message */
+		msg = osmo_cc_new_msg(OSMO_CC_MSG_ALERT_IND);
+		if (call->telephone_ep->early_audio && call->sdp) {
+			/* progress */
+			osmo_cc_add_ie_progress(msg, OSMO_CC_CODING_ITU_T, call->telephone_ep->serving_location, OSMO_CC_PROGRESS_INBAND_INFO_AVAILABLE);
+			/* sdp */
+			osmo_cc_add_ie_sdp(msg, call->sdp);
+			free((char *)call->sdp);
+			call->sdp = NULL;
+		}
+		/* send message to osmo-cc */
+		osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, msg);
+		/* change state */
+		call_new_state(call, CALL_STATE_IN_ALERTING);
+	}
+	if (c == 'c' && (call->state == CALL_STATE_IN_SETUP || call->state == CALL_STATE_IN_OVERLAP || call->state == CALL_STATE_IN_PROCEEDING || call->state == CALL_STATE_IN_ALERTING)) {
+		PDEBUG(DTEL, DEBUG_INFO, "Answer incoming call\n");
+		/* create osmo-cc message */
+		msg = osmo_cc_new_msg(OSMO_CC_MSG_SETUP_CNF);
+		/* sdp */
+		if (call->sdp) {
+			osmo_cc_add_ie_sdp(msg, call->sdp);
+			free((char *)call->sdp);
+			call->sdp = NULL;
+		}
+		/* send message to osmo-cc */
+		osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, msg);
+		/* change state */
+		call_new_state(call, CALL_STATE_CONNECT);
+	}
+	if (c > 0 && call->state == CALL_STATE_OUT_OVERLAP && strchr(ui_digits, c)) {
+		PDEBUG(DTEL, DEBUG_INFO, "Send digit %c\n", c);
+		char called[] = { c, '\0' };
+		/* create osmo-cc message */
+		msg = osmo_cc_new_msg(OSMO_CC_MSG_INFO_IND);
+		/* add dialing */
+		osmo_cc_add_ie_called(msg, OSMO_CC_TYPE_UNKNOWN, OSMO_CC_PLAN_TELEPHONY, called);
+		/* send message to osmo-cc */
+		osmo_cc_ll_msg(&call->telephone_ep->cc_ep, call->cc_callref, msg);
+		/* add to dial string */
+		append_string(ui_remote_id, sizeof(ui_remote_id), c);
+	}
+
+	/* NOTE: the state is from console view: a call towards CC is OUT and from CC is IN */
+	switch (call->state) {
+	case CALL_STATE_OUT_SETUP:
+	case CALL_STATE_OUT_PROCEEDING:
+	case CALL_STATE_OUT_ALERTING:
+		sprintf(text, "%s: %s (press h=hangup)\r", call_state_name[call->state], ui_remote_id);
+		break;
+	case CALL_STATE_OUT_OVERLAP:
+		sprintf(text, "%s: %s (press digits 0..9 h=hangup)\r", call_state_name[call->state], ui_remote_id);
+		break;
+	case CALL_STATE_CONNECT:
+		if (ui_remote_dialing[0])
+			sprintf(text, "%s: %s->%s (press h=hangup)\r", call_state_name[call->state], ui_remote_id, ui_remote_dialing);
+		else
+			sprintf(text, "%s: %s (press h=hangup)\r", call_state_name[call->state], ui_remote_id);
+		break;
+	case CALL_STATE_IN_DISCONNECT:
+		sprintf(text, "%s: %s (press h=hangup d=redial)\r", call_state_name[call->state], cause_name(ui_cause));
+		break;
+	case CALL_STATE_IN_SETUP:
+		sprintf(text, "%s: %s->%s (press o=overlap p=proceeding a=alerting c=connect h=hangup)\r", call_state_name[call->state], ui_remote_id, ui_remote_dialing);
+		break;
+	case CALL_STATE_IN_OVERLAP:
+		sprintf(text, "%s: %s->%s (press p=proceeding a=alerting c=connect h=hangup)\r", call_state_name[call->state], ui_remote_id, ui_remote_dialing);
+		break;
+	case CALL_STATE_IN_PROCEEDING:
+		sprintf(text, "%s: %s->%s (press a=alerting c=connect h=hangup)\r", call_state_name[call->state], ui_remote_id, ui_remote_dialing);
+		break;
+	case CALL_STATE_IN_ALERTING:
+		sprintf(text, "%s: %s->%s (press c=connect h=hangup)\r", call_state_name[call->state], ui_remote_id, ui_remote_dialing);
+		break;
+	default:
+		break;
+	}
+
+done:
+	/* skip if nothing has changed */
+	len = strlen(text);
+	if (ui_len == len && !memcmp(ui_text, text, len))
+		return work;
+	clear_console_text();
+	ui_len = len;
+	memcpy(ui_text, text, len);
+	memset(ui_clear, ' ', len - 1);
+	ui_clear[len - 1] = '\r';
+	print_console_text();
+	fflush(stdout);
+
+	return work;
+}
+