Multilink PPP with AO/DI support
In the case of Multilink PPP with AO/DI support, both analog devices can still be used as AO/DI uses the ISDN D-channel X-25 packet service to maintain an "always on" connection between you and your Service Provider. Low bandwidth requirements can be met using this constant connection, such as sending and receiving e-mail, credit card verification, etc.
For example, while a MLPPP data connection is in progress using both B-channels, one of your telephones rings. As soon as the phone rings, the MLPPP connection automatically drops one of the B- channels, reducing the data connection from 128 kbps to 64 kbps, and the voice call is then connected. If a fax call then comes in, the data call is passed to the D-channel, reducing the data connection from 64 kbps to 9.6 kbps and the fax call is connected.
After hanging up the voice calls, if the bandwidth is required the data connection re-establishes the B-channel and brings the data connection back up to 64 kbps. If the fax call is then hung up, the second B-channel will be re-established if the bandwidth is required. The same holds true if you decide to pick up the phone for an outgoing call.
DIVA T/A ISDN Modem User’s Guide 99
