static pjmedia_sdp_session *create_answer(int call_num, pj_pool_t *pool,
                                          const pjmedia_sdp_session *offer)
{
    const char* dir_attrs[] = { "sendrecv", "sendonly", "recvonly", "inactive" };
    const char *ice_attrs[] = {"ice-pwd", "ice-ufrag", "candidate"};
    pjmedia_sdp_session *answer = pjmedia_sdp_session_clone(pool, offer);
    pjmedia_sdp_attr *sess_dir_attr = NULL;
    unsigned mi;

    PJ_LOG(3,(THIS_FILE, "Call %d: creating answer:", call_num));

    answer->name = pj_str("sipecho");
    sess_dir_attr = find_remove_sdp_attrs(&answer->attr_count, answer->attr,
                                          PJ_ARRAY_SIZE(dir_attrs),
                                          dir_attrs);

    for (mi=0; mi<answer->media_count; ++mi) {
	pjmedia_sdp_media *m = answer->media[mi];
	pjmedia_sdp_attr *m_dir_attr;
	pjmedia_sdp_attr *dir_attr;
	const char *our_dir = NULL;
	pjmedia_sdp_conn *c;

	/* Match direction */
	m_dir_attr = find_remove_sdp_attrs(&m->attr_count, m->attr,
	                                   PJ_ARRAY_SIZE(dir_attrs),
	                                   dir_attrs);
	dir_attr = m_dir_attr ? m_dir_attr : sess_dir_attr;

	if (dir_attr) {
	    if (pj_strcmp2(&dir_attr->name, "sendonly")==0)
		our_dir = "recvonly";
	    else if (pj_strcmp2(&dir_attr->name, "inactive")==0)
		our_dir = "inactive";
	    else if (pj_strcmp2(&dir_attr->name, "recvonly")==0)
		our_dir = "inactive";

	    if (our_dir) {
		dir_attr = PJ_POOL_ZALLOC_T(pool, pjmedia_sdp_attr);
		dir_attr->name = pj_str((char*)our_dir);
		m->attr[m->attr_count++] = dir_attr;
	    }
	}

	/* Remove ICE attributes */
	find_remove_sdp_attrs(&m->attr_count, m->attr, PJ_ARRAY_SIZE(ice_attrs), ice_attrs);

	/* Done */
	c = m->conn ? m->conn : answer->conn;
	PJ_LOG(3,(THIS_FILE, "  Media %d, %.*s: %s <--> %.*s:%d",
		  mi, (int)m->desc.media.slen, m->desc.media.ptr,
		  (our_dir ? our_dir : "sendrecv"),
		  (int)c->addr.slen, c->addr.ptr, m->desc.port));
    }

    return answer;
}

static int parse_dtls_attrib(struct ast_sip_session_media *session_media,
	const struct pjmedia_sdp_media *stream)
{
	int i;
	struct ast_rtp_engine_dtls *dtls = ast_rtp_instance_get_dtls(session_media->rtp);

	for (i = 0; i < stream->attr_count; i++) {
		pjmedia_sdp_attr *attr = stream->attr[i];
		pj_str_t *value;

		if (!attr->value.ptr) {
			continue;
		}

		value = pj_strtrim(&attr->value);

		if (!pj_strcmp2(&attr->name, "setup")) {
			if (!pj_stricmp2(value, "active")) {
				dtls->set_setup(session_media->rtp, AST_RTP_DTLS_SETUP_ACTIVE);
			} else if (!pj_stricmp2(value, "passive")) {
				dtls->set_setup(session_media->rtp, AST_RTP_DTLS_SETUP_PASSIVE);
			} else if (!pj_stricmp2(value, "actpass")) {
				dtls->set_setup(session_media->rtp, AST_RTP_DTLS_SETUP_ACTPASS);
			} else if (!pj_stricmp2(value, "holdconn")) {
				dtls->set_setup(session_media->rtp, AST_RTP_DTLS_SETUP_HOLDCONN);
			} else {
				ast_log(LOG_WARNING, "Unsupported setup attribute value '%*s'\n", (int)value->slen, value->ptr);
			}
		} else if (!pj_strcmp2(&attr->name, "connection")) {
			if (!pj_stricmp2(value, "new")) {
				dtls->reset(session_media->rtp);
			} else if (!pj_stricmp2(value, "existing")) {
				/* Do nothing */
			} else {
				ast_log(LOG_WARNING, "Unsupported connection attribute value '%*s'\n", (int)value->slen, value->ptr);
			}
		} else if (!pj_strcmp2(&attr->name, "fingerprint")) {
			char hash_value[256], hash[32];
			char fingerprint_text[value->slen + 1];
			ast_copy_pj_str(fingerprint_text, value, sizeof(fingerprint_text));

			if (sscanf(fingerprint_text, "%31s %255s", hash, hash_value) == 2) {
				if (!strcasecmp(hash, "sha-1")) {
					dtls->set_fingerprint(session_media->rtp, AST_RTP_DTLS_HASH_SHA1, hash_value);
				} else if (!strcasecmp(hash, "sha-256")) {
					dtls->set_fingerprint(session_media->rtp, AST_RTP_DTLS_HASH_SHA256, hash_value);
				} else {
					ast_log(LOG_WARNING, "Unsupported fingerprint hash type '%s'\n",
					hash);
				}
			}
		}
	}
	ast_set_flag(session_media->srtp, AST_SRTP_CRYPTO_OFFER_OK);

	return 0;
}

/* Validate SDP connetion info. */
static pj_status_t validate_sdp_conn(const pjmedia_sdp_conn *c)
{
    CHECK( c, PJ_EINVAL);
    CHECK( pj_strcmp2(&c->net_type, "IN")==0, PJMEDIA_SDP_EINCONN);
    CHECK( pj_strcmp2(&c->addr_type, "IP4")==0 ||
	   pj_strcmp2(&c->addr_type, "IP6")==0, 
	   PJMEDIA_SDP_EINCONN);
    CHECK( c->addr.slen != 0, PJMEDIA_SDP_EINCONN);

    return PJ_SUCCESS;
}

/*!
 * \internal
 * \brief Checks to make sure the request has the correct content type.
 *
 * \details This module supports the following media types: "text/plain".
 * Return unsupported otherwise.
 *
 * \param rdata The SIP request
 */
static enum pjsip_status_code check_content_type(const pjsip_rx_data *rdata)
{
	int res;
	if (rdata->msg_info.msg->body && rdata->msg_info.msg->body->len) {
		res = ast_sip_is_content_type(
			&rdata->msg_info.msg->body->content_type, "text", "plain");
	} else {
		res = rdata->msg_info.ctype &&
			!pj_strcmp2(&rdata->msg_info.ctype->media.type, "text") &&
			!pj_strcmp2(&rdata->msg_info.ctype->media.subtype, "plain");
	}

	return res ? PJSIP_SC_OK : PJSIP_SC_UNSUPPORTED_MEDIA_TYPE;
}

/*! \brief Helper function which determines if the address within SDP should be rewritten */
static int multihomed_rewrite_sdp(struct pjmedia_sdp_session *sdp)
{
	if (!sdp->conn) {
		return 0;
	}

	/* If the host address is used in the SDP replace it with the address of what this is going out on */
	if ((!pj_strcmp2(&sdp->conn->addr_type, "IP4") && !pj_strcmp2(&sdp->conn->addr, host_ipv4)) ||
		(!pj_strcmp2(&sdp->conn->addr_type, "IP6") && !pj_strcmp2(&sdp->conn->addr, host_ipv6))) {
		return 1;
	}

	return 0;
}

/**
 * This method is to parse and add the argument attribute to command structure.
 **/
static pj_status_t add_arg_node(pj_cli_t *cli,
				pj_xml_node *xml_node,
				pj_cli_cmd_spec *cmd,
				pj_cli_arg_spec *arg,
				pj_cli_get_dyn_choice get_choice)
{    
    pj_xml_attr *attr;
    pj_status_t status = PJ_SUCCESS;
    pj_xml_node *sub_node = xml_node;

    if (cmd->arg_cnt >= PJ_CLI_MAX_ARGS)
	return PJ_CLI_ETOOMANYARGS;
    
    pj_bzero(arg, sizeof(*arg));
    attr = sub_node->attr_head.next;
    arg->optional = PJ_FALSE;
    arg->validate = PJ_TRUE;
    while (attr != &sub_node->attr_head) {	
	if (!pj_stricmp2(&attr->name, "name")) {
	    pj_strassign(&arg->name, &attr->value);
	} else if (!pj_stricmp2(&attr->name, "id")) {
	    arg->id = pj_strtol(&attr->value);
	} else if (!pj_stricmp2(&attr->name, "type")) {
	    if (!pj_stricmp2(&attr->value, "text")) {
		arg->type = PJ_CLI_ARG_TEXT;
	    } else if (!pj_stricmp2(&attr->value, "int")) {
		arg->type = PJ_CLI_ARG_INT;
	    } else if (!pj_stricmp2(&attr->value, "choice")) {
		/* Get choice value */
		add_choice_node(cli, xml_node, arg, get_choice);
	    } 
	} else if (!pj_stricmp2(&attr->name, "desc")) {
	    pj_strassign(&arg->desc, &attr->value);
	} else if (!pj_stricmp2(&attr->name, "optional")) {
	    if (!pj_strcmp2(&attr->value, "1")) {
		arg->optional = PJ_TRUE;
	    }
	} else if (!pj_stricmp2(&attr->name, "validate")) {
	    if (!pj_strcmp2(&attr->value, "1")) {
		arg->validate = PJ_TRUE;
	    } else {
		arg->validate = PJ_FALSE;
	    }	
	} 
	attr = attr->next;
    }
    cmd->arg_cnt++;
    return status;
}

PJ_DEF(pj_status_t) pjmedia_sdp_attr_get_fmtp( const pjmedia_sdp_attr *attr,
					       pjmedia_sdp_fmtp *fmtp)
{
    const char *p = attr->value.ptr;
    const char *end = attr->value.ptr + attr->value.slen;
    pj_str_t token;

    PJ_ASSERT_RETURN(pj_strcmp2(&attr->name, "fmtp")==0, PJ_EINVALIDOP);

    /* fmtp BNF:
     *	a=fmtp:<format> <format specific parameter>
     */

    /* Get format. */
    token.ptr = (char*)p;
    while (pj_isdigit(*p) && p!=end)
	++p;
    token.slen = p - token.ptr;
    if (token.slen == 0)
	return PJMEDIA_SDP_EINFMTP;

    fmtp->fmt = token;

    /* Expecting space after format. */
    if (*p != ' ') return PJMEDIA_SDP_EINFMTP;

    /* Get space. */
    ++p;

    /* Set the remaining string as fmtp format parameter. */
    fmtp->fmt_param.ptr = (char*)p;
    fmtp->fmt_param.slen = end - p;

    return PJ_SUCCESS;
}

static int setup_sdes_srtp(struct ast_sip_session_media *session_media,
	const struct pjmedia_sdp_media *stream)
{
	int i;

	for (i = 0; i < stream->attr_count; i++) {
		pjmedia_sdp_attr *attr;
		RAII_VAR(char *, crypto_str, NULL, ast_free);

		/* check the stream for the required crypto attribute */
		attr = stream->attr[i];
		if (pj_strcmp2(&attr->name, "crypto")) {
			continue;
		}

		crypto_str = ast_strndup(attr->value.ptr, attr->value.slen);
		if (!crypto_str) {
			return -1;
		}

		if (setup_srtp(session_media)) {
			return -1;
		}

		if (!ast_sdp_crypto_process(session_media->rtp, session_media->srtp, crypto_str)) {
			/* found a valid crypto attribute */
			return 0;
		}

		ast_debug(1, "Ignoring crypto offer with unsupported parameters: %s\n", crypto_str);
	}

	/* no usable crypto attributes found */
	return -1;
}

static pj_status_t server_get_password( const pj_stun_msg *msg,
					void *user_data, 
				        const pj_str_t *realm,
				        const pj_str_t *username,
					pj_pool_t *pool,
					pj_stun_passwd_type *data_type,
					pj_str_t *data)
{
    PJ_UNUSED_ARG(msg);
    PJ_UNUSED_ARG(user_data);
    PJ_UNUSED_ARG(pool);

    if (server->auth_type == PJ_STUN_AUTH_SHORT_TERM) {
	if (realm && realm->slen) {
	    PJ_LOG(4,(THIS_FILE, "    server expecting short term"));
	    return -1;
	}
    } else {
	if (realm==NULL || realm->slen==0) {
	    PJ_LOG(4,(THIS_FILE, "    realm not present"));
	    return -1;
	}
    }

    if (pj_strcmp2(username, USERNAME) != 0) {
	PJ_LOG(4,(THIS_FILE, "    wrong username"));
	return -1;
    }

    *data_type = PJ_STUN_PASSWD_PLAIN;
    *data = pj_str(PASSWORD);

    return PJ_SUCCESS;
}

static pj_bool_t my_on_rx_request(pjsip_rx_data *rdata)
{
    /* Check that this is our request. */
    if (pj_strcmp2(&rdata->msg_info.cid->id, CALL_ID_HDR) == 0) {
	/* It is! */
	/* Send response. */
	pjsip_tx_data *tdata;
	pjsip_response_addr res_addr;
	pj_status_t status;

	status = pjsip_endpt_create_response( endpt, rdata, 200, NULL, &tdata);
	if (status != PJ_SUCCESS) {
	    recv_status = status;
	    return PJ_TRUE;
	}
	status = pjsip_get_response_addr( tdata->pool, rdata, &res_addr);
	if (status != PJ_SUCCESS) {
	    recv_status = status;
	    pjsip_tx_data_dec_ref(tdata);
	    return PJ_TRUE;
	}
	status = pjsip_endpt_send_response( endpt, &res_addr, tdata, NULL, NULL);
	if (status != PJ_SUCCESS) {
	    recv_status = status;
	    pjsip_tx_data_dec_ref(tdata);
	    return PJ_TRUE;
	}
	return PJ_TRUE;
    }
    
    /* Not ours. */
    return PJ_FALSE;
}

static pj_bool_t my_on_rx_response(pjsip_rx_data *rdata)
{
    if (pj_strcmp2(&rdata->msg_info.cid->id, CALL_ID_HDR) == 0) {
	pj_get_timestamp(&my_recv_time);
	recv_status = PJ_SUCCESS;
	return PJ_TRUE;
    }
    return PJ_FALSE;
}

static int verify_part(pjsip_multipart_part *part,
		       char *h_content_type,
		       char *h_content_subtype,
		       char *boundary,
		       int h_content_length,
		       const char *body)
{
    pjsip_ctype_hdr *ctype_hdr = NULL;
    pjsip_clen_hdr *clen_hdr = NULL;
    pjsip_hdr *hdr;
    pj_str_t the_body;

    hdr = part->hdr.next;
    while (hdr != &part->hdr) {
	if (hdr->type == PJSIP_H_CONTENT_TYPE)
	    ctype_hdr = (pjsip_ctype_hdr*)hdr;
	else if (hdr->type == PJSIP_H_CONTENT_LENGTH)
	    clen_hdr = (pjsip_clen_hdr*)hdr;
	hdr = hdr->next;
    }

    if (h_content_type) {
	pjsip_media_type mt;

	if (ctype_hdr == NULL)
	    return -10;

	init_media_type(&mt, h_content_type, h_content_subtype, boundary);

	if (pjsip_media_type_cmp(&ctype_hdr->media, &mt, 2) != 0)
	    return -20;

    } else {
	if (ctype_hdr)
	    return -30;
    }

    if (h_content_length >= 0) {
	if (clen_hdr == NULL)
	    return -50;
	if (clen_hdr->len != h_content_length)
	    return -60;
    } else {
	if (clen_hdr)
	    return -70;
    }

    the_body.ptr = (char*)part->body->data;
    the_body.slen = part->body->len;

    if (pj_strcmp2(&the_body, body) != 0)
	return -90;

    return 0;
}

PJ_DEF(pj_status_t) pjmedia_sdp_attr_get_rtcp(const pjmedia_sdp_attr *attr,
					      pjmedia_sdp_rtcp_attr *rtcp)
{
    pj_scanner scanner;
    pj_str_t token;
    pj_status_t status = -1;
    PJ_USE_EXCEPTION;

    PJ_ASSERT_RETURN(pj_strcmp2(&attr->name, "rtcp")==0, PJ_EINVALIDOP);

    init_sdp_parser();

    /* fmtp BNF:
     *	a=rtcp:<port> [nettype addrtype address]
     */

    pj_scan_init(&scanner, (char*)attr->value.ptr, attr->value.slen,
		 PJ_SCAN_AUTOSKIP_WS, &on_scanner_error);

    /* Init */
    rtcp->net_type.slen = rtcp->addr_type.slen = rtcp->addr.slen = 0;

    /* Parse */
    PJ_TRY {

	/* Get the port */
	pj_scan_get(&scanner, &cs_token, &token);
	rtcp->port = pj_strtoul(&token);

	/* Have address? */
	if (!pj_scan_is_eof(&scanner)) {

	    /* Get network type */
	    pj_scan_get(&scanner, &cs_token, &rtcp->net_type);

	    /* Get address type */
	    pj_scan_get(&scanner, &cs_token, &rtcp->addr_type);

	    /* Get the address */
	    pj_scan_get(&scanner, &cs_token, &rtcp->addr);

	}

	status = PJ_SUCCESS;

    }
    PJ_CATCH_ANY {
	status = PJMEDIA_SDP_EINRTCP;
    }
    PJ_END;

    pj_scan_fini(&scanner);
    return status;
}

static int format_test(void)
{
    pj_str_t s = pj_str(ADDRESS);
    unsigned char *p;
    pj_in_addr addr;
    char zero[64];
    pj_sockaddr_in addr2;
    const pj_str_t *hostname;

    PJ_LOG(3,("test", "...format_test()"));
    
    /* pj_inet_aton() */
    if (pj_inet_aton(&s, &addr) != 1)
	return -10;
    
    /* Check the result. */
    p = (unsigned char*)&addr;
    if (p[0]!=A0 || p[1]!=A1 || p[2]!=A2 || p[3]!=A3) {
	PJ_LOG(3,("test", "  error: mismatched address. p0=%d, p1=%d, "
			  "p2=%d, p3=%d", p[0] & 0xFF, p[1] & 0xFF, 
			   p[2] & 0xFF, p[3] & 0xFF));
	return -15;
    }

    /* pj_inet_ntoa() */
    p = (unsigned char*) pj_inet_ntoa(addr);
    if (!p)
	return -20;

    if (pj_strcmp2(&s, (char*)p) != 0)
	return -30;

    /* Test that pj_sockaddr_in_init() initialize the whole structure, 
     * including sin_zero.
     */
    pj_sockaddr_in_init(&addr2, 0, 1000);
    pj_bzero(zero, sizeof(zero));
    if (pj_memcmp(addr2.sin_zero, zero, sizeof(addr2.sin_zero)) != 0)
	return -35;

    /* pj_gethostname() */
    hostname = pj_gethostname();
    if (!hostname || !hostname->ptr || !hostname->slen)
	return -40;

    PJ_LOG(3,("test", "....hostname is %.*s", 
	      (int)hostname->slen, hostname->ptr));

    /* pj_gethostaddr() */


    return 0;
}

static struct ast_sip_aor *find_aor(struct ast_sip_endpoint *endpoint, pjsip_uri *uri)
{
	char *configured_aors, *aor_name;
	pjsip_sip_uri *sip_uri;
	char *domain_name;
	RAII_VAR(struct ast_str *, id, NULL, ast_free);

	if (ast_strlen_zero(endpoint->aors)) {
		return NULL;
	}

	sip_uri = pjsip_uri_get_uri(uri);
	domain_name = ast_alloca(sip_uri->host.slen + 1);
	ast_copy_pj_str(domain_name, &sip_uri->host, sip_uri->host.slen + 1);

	configured_aors = ast_strdupa(endpoint->aors);

	/* Iterate the configured AORs to see if the user or the user+domain match */
	while ((aor_name = strsep(&configured_aors, ","))) {
		struct ast_sip_domain_alias *alias = NULL;

		if (!pj_strcmp2(&sip_uri->user, aor_name)) {
			break;
		}

		if (!id && !(id = ast_str_create(sip_uri->user.slen + sip_uri->host.slen + 2))) {
			return NULL;
		}

		ast_str_set(&id, 0, "%.*[email protected]", (int)sip_uri->user.slen, sip_uri->user.ptr);
		if ((alias = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "domain_alias", domain_name))) {
			ast_str_append(&id, 0, "%s", alias->domain);
			ao2_cleanup(alias);
		} else {
			ast_str_append(&id, 0, "%s", domain_name);
		}

		if (!strcmp(aor_name, ast_str_buffer(id))) {
			ast_free(id);
			break;
		}
	}

	if (ast_strlen_zero(aor_name)) {
		return NULL;
	}

	return ast_sip_location_retrieve_aor(aor_name);
}

/*!
 * \brief Lookup callback for authentication verification
 *
 * This function is called when we call pjsip_auth_srv_verify(). It
 * expects us to verify that the realm and account name from the
 * Authorization header is correct. We are then supposed to supply
 * a password or MD5 sum of credentials.
 *
 * \param pool A memory pool we can use for allocations
 * \param realm The realm from the Authorization header
 * \param acc_name the user from the Authorization header
 * \param[out] info The credentials we need to fill in
 * \retval PJ_SUCCESS Successful authentication
 * \retval other Unsuccessful
 */
static pj_status_t digest_lookup(pj_pool_t *pool, const pj_str_t *realm,
		const pj_str_t *acc_name, pjsip_cred_info *info)
{
	RAII_VAR(struct ast_sip_auth *, auth, get_auth(), ao2_cleanup);
	if (!auth) {
		return PJSIP_SC_FORBIDDEN;
	}

	if (auth->type == AST_SIP_AUTH_TYPE_ARTIFICIAL) {
		return PJSIP_SC_FORBIDDEN;
	}

	if (pj_strcmp2(realm, auth->realm)) {
		return PJSIP_SC_FORBIDDEN;
	}
	if (pj_strcmp2(acc_name, auth->auth_user)) {
		return PJSIP_SC_FORBIDDEN;
	}

	pj_strdup2(pool, &info->realm, auth->realm);
	pj_strdup2(pool, &info->username, auth->auth_user);

	switch (auth->type) {
	case AST_SIP_AUTH_TYPE_USER_PASS:
		pj_strdup2(pool, &info->data, auth->auth_pass);
		info->data_type = PJSIP_CRED_DATA_PLAIN_PASSWD;
		break;
	case AST_SIP_AUTH_TYPE_MD5:
		pj_strdup2(pool, &info->data, auth->md5_creds);
		info->data_type = PJSIP_CRED_DATA_DIGEST;
		break;
	default:
		return PJSIP_SC_FORBIDDEN;
	}
	return PJ_SUCCESS;
}

static int find_challenge(const pjsip_rx_data *rdata, const struct ast_sip_auth *auth)
{
	struct pjsip_authorization_hdr *auth_hdr = (pjsip_authorization_hdr *) &rdata->msg_info.msg->hdr;
	int challenge_found = 0;
	char nonce[64];

	while ((auth_hdr = (pjsip_authorization_hdr *) pjsip_msg_find_hdr(rdata->msg_info.msg, PJSIP_H_AUTHORIZATION, auth_hdr->next))) {
		ast_copy_pj_str(nonce, &auth_hdr->credential.digest.nonce, sizeof(nonce));
		if (check_nonce(nonce, rdata, auth) && !pj_strcmp2(&auth_hdr->credential.digest.realm, auth->realm)) {
			challenge_found = 1;
			break;
		}
	}

	return challenge_found;
}

static pj_bool_t server_verify_nonce(const pj_stun_msg *msg,
				     void *user_data,
				     const pj_str_t *realm,
				     const pj_str_t *username,
				     const pj_str_t *nonce)
{
    PJ_UNUSED_ARG(msg);
    PJ_UNUSED_ARG(user_data);
    PJ_UNUSED_ARG(realm);
    PJ_UNUSED_ARG(username);

    if (pj_strcmp2(nonce, NONCE) != 0)
	return PJ_FALSE;

    return PJ_TRUE;
}

/// Checks whether the supplied message contains the extension in the
/// Supported header.
pj_bool_t PJUtils::msg_supports_extension(pjsip_msg* msg, const char* extension)
{
  pjsip_supported_hdr* supported_hdr = (pjsip_supported_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_SUPPORTED, NULL);
  if (!supported_hdr)
  {
    return PJ_FALSE;
  }
  for (unsigned ii = 0; ii < supported_hdr->count; ++ii)
  {
    if (pj_strcmp2(&supported_hdr->values[ii], extension) == 0)
    {
      return PJ_TRUE;
    }
  }
  return PJ_FALSE;
}

/*! \brief Callback for when T.38 reinvite SDP is created */
static int t38_reinvite_sdp_cb(struct ast_sip_session *session, pjmedia_sdp_session *sdp)
{
	int stream;

	/* Move the image media stream to the front and have it as the only stream, pjmedia will fill in
	 * dummy streams for the rest
	 */
	for (stream = 0; stream < sdp->media_count++; ++stream) {
		if (!pj_strcmp2(&sdp->media[stream]->desc.media, "image")) {
			sdp->media[0] = sdp->media[stream];
			sdp->media_count = 1;
			break;
		}
	}

	return 0;
}