5-2 CHAPTER 5: ADVANCED CONFIGURATION

QuickSelect

The QuickSelect feature (S71=0, by default) automatically detects and implements the protocol required for each digital call, either V.120 or Async-Sync PPP. Typically, V.120 is used for communication between two computers, whereas

PPPis used for communication between a computer and an Internet service provider.

Dynamic Bandwidth Allocation

DBA (S70=3, by default) is a method of automatically reallocating bandwidth to allow you to place or receive a voice call while a Multilink PPP call is active (i.e., both B channels are in use).

In this situation, when you lift the handset to place an outgoing call or to answer an incoming call, one of the B channels is temporarily removed from the Multilink PPP call and is used for the voice call.

Once the voice call ends, that B channel is automatically returned to the Multilink PPP call. Although throughput is reduced to one channel while the voice call is active, the integrity of the Multilink PPP call is maintained.

If you are on the receiving end of a Multilink PPP call (i.e., someone has dialed into your 3C882 ISDN modem) and you place a voice call, one of the B channels will still be allocated for the new voice call. However, once the voice call ends, that B channel cannot be returned to the incoming Multilink PPP call. The B channel can only be returned to the Multilink PPP call for outgoing Multilink PPP calls.

Outgoing DBA takes precedence over incoming DBA. For example, during a Multilink PPP call, you receive an incoming voice call over Phone port 1. You may, however, prefer to place an outgoing call over Phone port 2 and ignore the incoming call. When you place your call over Phone port 2,