7. cfg_msn: Configuration/MSNs

7.1 cfg_msn_my1: What is my MSN?

Your telephone company will tell you your MSN. It is your own telephone number. If you don't know your MSN, then check section countries , together with the following questions.

7.2 cfg_msn_my2: How can I find out how my telephone number is transmitted to the calling party?

The transmitted MSN can simply be determined by calling yourself (for example by telephone). In the log files you will find the entry that looks like: "isdn_tty: call from XXX - YYY ignored" (in order for this to work, you must of course already have the ISDN drivers in your kernel and active).

7.3 cfg_msn_config: How do I configure my MSN?

If your telephone number were 56789, then it would be configured as follows:

• Modem emulation: "AT&e56789"
• Network interfaces: "isdnctrl msn interface 56789"
• For test calls to yourself add the area code (e.g. 01234):

  ---

  "isdnctrl addphone interface in 123456789" (without leading zero)
  "isdnctrl addphone interface out 0123456789" (with leading zero)
  

  ---

7.4 cfg_msn_mindialin: How can I minimize usage of MSNs for digital data dialin?

i4l gives priority to net interfaces. Therefore, you can get away with only one MSN when you set it up like this:

1. Set up net interfaces (sync ppp, rawip) for all users that will want to use them (ipppd or rawip), with their incoming phone number (precondition is that it is transmitted).
2. Set up ttyI* for all other users (X.75, async ppp).
3. Set option `secure on'.

7.5 cfg_msn_onlyone: How can I use one MSN for everything?

Digital data dialin can easily be distinguished from voice/analog modem dialin by the 'Service Recognition' code ("digital, data").

For the differentiation between net interfaces (ipppd, rawip) and ttyI* (X.75) see last question.

To get voice/analog modem to work in parallel, use mgetty for the analog modem. Mgetty can handle analog data calls, faxes, and even voice calls as answering machine if the modem supports it. Configure it for 10 rings. If you take the phone and hear a fax or modem, send mgetty a USR1 signal (kill -USR1 mgetty-pid). If your phone socket is correctly wired, the modem will take over the connection, cutting off the phone. If you have an ISDN PBX then you can forward the call to a different analog port when you picked up a fax/modem call.

If your analog modem can not handle voice calls, then you have to choose since incoming voice calls can not be distinguished from analog fax/data calls. Use either VBOX to take your voice calls as an answering machine. Or forget about voice calls and set up your modem to handle only faxes and/or analog data calls.

7.6 cfg_msn_buendel: Can I have several NTBAs, all with the same MSN?

Yes, but you need the cooperation of your telecommunication company. They can set up several BRIs in Point-to-point mode that have the same MSN. In Germany it is called a bundled line (`Bündelanschluß').