Telephony42
Last updated: 2026-08-18
Contact: Telegram @cloudc001 | Email: cloudc001#outlook.com
Overview#
CloudC Telephony42 is my DN42 voice service. It provides SIP-based calling, ENUM routing, test numbers, and a few small voice services inside DN42.
CloudC Telephony42 是我在 DN42 内运行的电话服务，主要用于 DN42 内部 SIP 通话、ENUM 解析、测试拨号和一些有趣的语音服务。
| Item | Value |
|---|---|
| Network | CloudC DN42 |
| ASN | AS4242423777 |
| DN42 IPv4 Prefix | 172.22.107.0/27 |
| DN42 IPv6 Prefix | fdbb:aee:d9bd::/48 |
| Telephony42 Prefix | +04243777 |
| Main SIP Node | 172.22.107.9 |
| Backup / Related Nodes | HK and other CloudC DN42 nodes |
| ENUM Zone | 7.7.7.3.4.2.4.0.tel.dn42 |
| Primary Domain | cloudc.dn42 |
| Public Status | Best effort |
info
This service is experimental and operated as part of my DN42 lab. Please do not depend on it for emergency calling or production telephony.
这是一个 DN42 实验性电话服务，请不要把它用于紧急电话或生产级语音服务。
Number Plan#
CloudC Telephony42 numbers use the following prefix:
+04243777XXXXShort internal extensions may also be available when you are directly connected to my SIP service.
| Number | Type | Description |
|---|---|---|
+042437771001 | Extension | CloudC user extension |
+042437771002 | Extension | CloudC user extension |
+04243777 | Prefix | CloudC Telephony42 number prefix |
+042437770000 | Service | Alarm clock IVR |
note
Some internal short numbers, such as 0000 and 3777, are mainly intended for users already registered to the CloudC SIP service.
Service Numbers#
3777 — Test Voice#
Use this number to verify that SIP signaling and RTP audio are working.
建议先拨打 3777 测试语音。如果这个号码可以听到声音，说明基础 SIP/RTP 链路基本正常。
0000 — Alarm Clock IVR#
The alarm clock service allows a caller to create callback alarms using DTMF input.
闹钟服务允许用户通过电话按键设置回拨提醒。
Basic usage:
| Action | Input |
|---|---|
| Add alarm | Enter HHMM, for example 2359 |
| Query alarms | Press * |
| Clear alarms | In the query menu, press # |
| Delete one alarm | In the query menu, press 1# to 9# |
Limits:
- Each extension can have up to 9 active alarms.
- Alarm callback uses the caller extension as the callback target.
- If your SIP client is offline when the alarm fires, the callback may fail.
Public Directory#
| Number | Short Number | Name | Usage |
|---|---|---|---|
+042437771001 | 1001 | CloudC user | Personal / test extension |
+042437771002 | 1002 | CloudC user | Personal / test extension |
+04243777 | Prefix | CloudC prefix | Telephony42 number prefix |
+042437770000 | 0000 | Alarm clock | Multi-alarm IVR |
| Internal only | Admin | CloudC admin | Administrator-only short numbers |
If you want to be listed here, please contact me first.
How to Call#
From Telephony42 / DN42#
If your PBX supports ENUM under tel.dn42, you should be able to dial the full E.164-like Telephony42 number:
+042437771001+042437771002Your PBX should resolve the corresponding NAPTR record and route the call to my SIP service.
From CloudC Internal SIP#
If you have a registered internal extension, you may dial short service numbers directly:
1001100237770000SIP Client Setup Notes#
The exact SIP account details are not published here. If you need a test account, contact me.
Recommended Client Behavior#
Use one stable SIP registration method per extension. If you need a test account or special access method, please contact me first.
tip
Avoid registering the same extension from many clients at the same time. Stale SIP contacts may cause callbacks to fail.
Known Working Clients#
| Client | Platform | Notes |
|---|---|---|
| MicroSIP | Windows | Good for LAN or routed DN42 testing |
| MizuDroid | Android | Works, but Android background restrictions may affect registration |
| Linphone | Android / Desktop | Works, but verify transport and registration status |
| Yealink SIP phones | Hardware | Recommended for stable LAN usage |
Troubleshooting#
Registered but No Audio#
Likely causes:
- RTP path is blocked.
- SIP client advertises an unreachable media address.
- The network path does not forward RTP reliably.
- NAT or firewall rewrites the signaling but not the media path.
Suggested checks:
- Dial
3777. - Confirm both sides can exchange RTP.
- Avoid direct media between clients.
- Use one stable transport per extension.
Alarm Does Not Call Back#
Likely causes:
- The extension is offline when the alarm fires.
- The same extension has multiple stale SIP contacts.
- The extension has stale or conflicting SIP contacts.
- The PBX cannot create an outgoing PJSIP dialog.
Suggested checks:
pjsip show contactspjsip show endpoint 1002Stale SIP Contacts#
If callback calls fail after switching clients, the extension may still have stale SIP contacts. Re-register the SIP client or contact me to clear old contacts.
DNS and ENUM#
CloudC Telephony42 uses ENUM-style DNS records under:
7.7.7.3.4.2.4.0.tel.dn42The main CloudC DN42 domain is:
cloudc.dn42DNSSEC is enabled for the relevant zones.
note
If your resolver cannot resolve tel.dn42 or cloudc.dn42, verify your DN42 DNS setup first.
Operations Policy#
- This is a best-effort DN42 hobby service.
- Abuse, scanning, or repeated invalid calls may be blocked.
- Service numbers may change as the project evolves.
- Internal/private extension credentials are not published.
- Debug information may be logged for troubleshooting.
Changelog#
2026-08#
- Prepared public Docusaurus documentation for CloudC Telephony42.
2026-07#
- Deployed CloudC Telephony42 services.
- Added ENUM/NAPTR records for the CloudC Telephony42 prefix.
- Added
3777test voice service. - Added
0000multi-alarm IVR service. - Tested MicroSIP, MizuDroid, and hardware phone planning.
Contact#
For Telephony42 peering, testing, or directory updates:
- Telegram: @cloudc001
- Email:
cloudc001#outlook.com
Please mention your DN42 ASN and the number/service you want to test.