There should be no problem for a modern modem to create a connect to CoMa Mailbox. Every modem should send a data-calling-tone and everything works automatically. If this is not the case you have to trick the modem to make a data-connect. (Do you like the politicians word "should"? and the "trick" analogy applies as well.) The main condition for this is that you have activated data-connect in the pop-up-menu "Connect". 
We will now show you two tricks which work with bad hardware as well:
1. Recognition of silence
You call the mailbox with a modem and the answering text is played to you first. After that CoMa records for 7 seconds. If silence is not recognised during this time CoMa tries to make a data-connect. It is absolutely necessary that the Register S7 is configured correctly for this otherwise the time to detect the data carrier is not sufficient. Furthermore, the modem has to be able to detect the silence cleanly.
2. Manual access with DTMF key 9
You call the mailbox with a telephone and press key 9 when you hear the answering text. CoMa interrupts the announcement and tries to make a data-connect at once. You have to switch the connection to the modem quickly after pressing 9.
This normally functions very well if you have called up your terminal programme and entered the string ATD. After CoMa interrupts the announcement you press the return key and the modem will take over the connection and build a connection to the mailbox.
Automatic connection with the data-calling-tone
The most commonly used modem types, amongst others all modem types with BZT, send a data-calling-tone when making a data call. If your reception modem recognises the tone and reports to CoMa the announcement will be interrupted and the programme tries to make a data connect at once.
Problems with the data-calling-tone
This functions only from firmware 6.11 for ZyXEL modems! The transer to data mode does not function at all for Creatix LC 144 VF in the firmware 1.4. The firmware 1.5 from June 94 upwards does not have this problem any more. A further problem that can happen with receiving modems (e.g. USRobotics Sportster) is that the data-calling-tone is unrecognised. In this case no data-connect can take place. There are two solutions, the first is apply rule 2 above, the second (and best) is get a better modem.
