Simon Marsh
76fc869170
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70 lines
2.8 KiB
Markdown
70 lines
2.8 KiB
Markdown
---
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title: "Dialup Service"
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geekdocDescription: "Modem Dialup Service"
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weight: 10
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---
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Connect in to dn42 using a real physical modem.
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{{<hint danger>}}
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**06/02/23** - The modem service is currently unavailable and will remain offline until later in the year.
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In the meantime, the [modem emulator](https://wdev.burble.dn42/retro/fake/) service is still available.
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{{</hint>}}
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{{<hint warning>}}
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**Health warning**: dialing in to dn42 can be rewarding and great fun, but using modems
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over VoIP is flakey at the best of times and getting it to work can be a
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frustrating experience. This is very much an experimental service.
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{{</hint>}}
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The burble.dn42 dialup service allows you to dial in to dn42 via a modem. The
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modem is reachable via VoIP and connected to a PPP server, allowing you to log in
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and obtain full dn42 IPv4 connectivity.
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#### Endpoints
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The dialup service can be reached via the following endpoints:
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| Endpoint | Network |
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|:--|:--|
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| 424026019@voip.burble.dn42 | dn42 |
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| *tbc* | clearnet |
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| *tbc* | PSTN |
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#### PPP Server Log In Details
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- Username: dn42
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- Password: dn42
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See also the the [modem emulator](/retro/fake) for more details on
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how the PPP server is configured, together with an automatic login
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script for windows variants.
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## Connection Tips
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- Ensure that T.38 Fax Mode is disabled or set to passthrough
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- Ensure that Re-invite after Fax Tone is disabled
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- Ensure that all Echo Cancelation is disabled
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- Ensure VAD (Voice Activity Detection) is disabled
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- Disable all call features (voicemail, call waiting etc.)
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- Use G.711 ALAW
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- G.711 ULAW may work if ALAW isn't available, but do not use any other codecs
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- Experiment with Disabling/Fixed/Adaptive Jitter buffers and different jitter buffer lengths
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- Experiment with different gain settings
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- Reduce modulation rates, you can't connect at anything above V.34 anyway
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- Use `AT+MS?` to see the current modulation settings on your modem.
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- Start at V.34 (`AT+MS=V34`)
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- Try V.32bis (`AT+MS=V32b`) or even V.32 (`AT+MS=V32`)
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- The modems are located on a residential DSL connection and will experience more jitter when the DSL is in use, try connecting at different times and specifically during UK night time or early mornings.
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- The PPP log in process is the same as the [modem emulator](/retro/fake) so you can use the
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emulator to check your process before connecting using the modem.
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## Example connection from linux
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The video shows an example connecting using minicom and pppd on linux.
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<video src="/retro/modem.webm" width="720" height="449" autoplay="true" loop="true"></video>
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## Using a software modem
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[JerryXiao](https://jerryxiao.cc/dn42) has created instructions for connecting using D-Modem, a software modem that can connect directly over VoIP. The instructions and D-Modem software are available in the [dn42 gitea repository](https://git.dn42.dev/JerryXiao/D-Modem/src/branch/master/README.jerry.md). |