The telecommuter application of the IP Softphone requires the use of one telephone line for the IP connection to Communication Manager, which is used for softphone registration and call signaling, and one for a PSTN connection, which Communication Manager uses as a callback number to establish the voice path. How you allocate your telephone lines to these two functions can make a difference.

For example, assume that you have voice mail provided by the local telephone company on one of your lines and not the other. In this case, you should use the line with the voice mail to make the initial IP connection to register the Softphone and use the line without voice mail as the POTS callback for the voice path. Otherwise, there could be undesirable interactions between the Softphone and the local voice mail service. For example, if your telecommuter application is registered and you were using your POTS callback line for a personal call when a business associate dialed your work extension, the business associate would hear your home voice mail message.