First things first: The command set. This is a fairly long list and it isn't comprehensive. More information can be found on the internet. All commands are preceded by "AT" unless otherwise noted.
| E(0/1) | E0 Turns off echoing of command characters. E1 turns them on. |
| L(0-3) | L0 sets speaker volume to the lowest level. L3 sets it to the highest. L1 and L2 are somewhere in the middle. |
| M(0-3) | M0 turns the speaker off. M1 sets the speaker off until a carrier is detected. M2 sets the speaker to be always on. M3 turns the speaker on during answering only. |
| P | Use pulse dialing |
| T | Use tone dialing |
| Z(0/1) | Z0 set modem to profile 0. Z1 set modem to profile 1. |
| %F | Load factory profile |
| Sn=m | Set "S" register n to value m. |
Let's look at the default init string: "AT&FE0S7=45S0=0L2." All commands must be preceeded by "AT." "&F" loads the factory profile. "E0" tells the modem not to echo commands. Since MacDialer doesn't show these commands, there is no reason to have them echoed. "S7=45" sets the S7 register to 45 and "S0=0" sets the S0 register to 0. Finally, "L2" sets the speaker volume to mid-high.
If you wanted to adjust the wait time when using the pause (",") character, you could modify this init string to do so. The S8 register holds the value for the length of the pause (information on the registers and what they do can be found online), so you have to put a different value in. The default is 2 seconds or so on most modems. Let's expand that to 3 seconds by using the code "S8=3." That puts the value "3" into the S8 register. Also, we don't want to hear the phone while it is dialing, so let's use the command "L0" to turn it down. We've already got "L2" in our default init string, so we need to replace it with "L0." Our modem will have longer pauses and be quieter if we put "AT&F1E0S7-45S0=0L0S8=3" as out init string.