Insert pauses in the number your modem dials on Mac
If you are calling from a phone line that requires you to dial a number (such as 9) for an outside line, or you need your modem to pause for some reason when dialing a number, use a comma (,) after the number to insert a 1-second pause. This gives the phone enough time to establish a connection with an outside line.
Use multiple commas for a longer pause.
On your Mac, choose Apple menu > System Preferences, then click Network.
Select your modem in the list at the left.
If your modem is not in the list, make sure your modem is connected to your computer (internally or externally), click the Add button at the bottom of the list, click the Interface pop-up menu, then choose Modem. Give your modem service a name, then click Create.
Enter the telephone number, account name, and password if necessary.
Enter a comma (,) where you want to add the pause. Use multiple commas for a longer pause.