昨天处理客户提出的话机设置呼叫转移不生效的问题，
经过多次测试发现这个问题与freeswitch版本和配置没有关系，
后来分析freeswitch正常转移日志与不转移日志发现不转移的日志少了一行 Redirect : transfering to *** ,
然后根据这个日志从freeswitch的Sofia模块6753行前后中找到相关代码，
if (sofia_test_pflag(profile, PFLAG_MANUAL_REDIRECT)) {
if (!(v = switch_channel_get_variable(channel, "outbound_redirect_info"))) {
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_DEBUG, "Redirect: Transfering to %s %s %s\n",
p_contact->m_url->url_user, sip_redirect_dialplan, sip_redirect_context);
if (switch_true(switch_channel_get_variable(channel, "recording_follow_transfer"))) {
switch_core_media_bug_transfer_recordings(session, a_session);
}
switch_ivr_session_transfer(a_session, p_contact->m_url->url_user, sip_redirect_dialplan, sip_redirect_context);
}
switch_channel_hangup(channel, SWITCH_CAUSE_REDIRECTION_TO_NEW_DESTINATION);
} else if( !p_contact->m_url->url_host ) {
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_WARNING, "Received redirect with invalid URI\n");
switch_channel_set_variable(channel, SWITCH_ENDPOINT_DISPOSITION_VARIABLE, "REDIRECT_ERROR");
switch_channel_hangup(channel, SWITCH_CAUSE_DESTINATION_OUT_OF_ORDER);
} else if ((!strcmp(profile->sipip, p_contact->m_url->url_host))
|| (profile->extsipip && !strcmp(profile->extsipip, p_contact->m_url->url_host))
|| (switch_xml_locate_domain(p_contact->m_url->url_host, NULL, &root, &domain) == SWITCH_STATUS_SUCCESS)) {
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_DEBUG, "Redirect: Transfering to %s\n",
p_contact->m_url->url_user);
if (switch_true(switch_channel_get_variable(channel, "recording_follow_transfer"))) {
switch_core_media_bug_transfer_recordings(session, a_session);
}
switch_ivr_session_transfer(a_session, p_contact->m_url->url_user, NULL, NULL);
switch_channel_hangup(channel, SWITCH_CAUSE_REDIRECTION_TO_NEW_DESTINATION);
switch_xml_free(root);
} else {
invite_contact = sofia_glue_strip_uri(full_contact);
tech_pvt->redirected = switch_core_session_strdup(session, invite_contact);
free(invite_contact);
}
并把相关判断条件打印出来发现是因为专有网络从服务器上获取不到外网ip地址导致的，
根据switch_xml_locate_domain的判断条件让directory返回域名信息就可以解决了。
