Reference Guide for the Model XM128 ISDN Digital Modem
If you want the Model XM128 modem to answer inbound calls using all possible protocols, refer to Table 6-4 for the commands used to set the best-effort call answering bit.
Table 6-4. | Best-effort call answering bit commands |
| |
Command | Function |
| |
ATS119.3=0 | Answer call only when number matched (by default) |
ATS119.3=1 | Best-effort call answering |
| |
Ambiguity Resolution Switch for Voice Calls
For a speech or voice-band-data call, if the &ZI number assignment can tell which of the analog adapters is being addressed, then the call is delivered to the proper destination. Sometimes, however, ambiguity of address matching may exist. This ambiguity may exist if the &ZIn numbers of the various protocols are either unassigned or not matched or the address information is absent in the incoming setup message. In this case, users may want to set answering priority to an analog port. The AT&Ln command sets the address ambiguity resolution flag as follows:
•AT&L0
The analog adapter 1 has the higher priority to answer a voice or voice-band-analog-data call. If the analog adapter 1 is busy, the call is routed to the analog adapter, PHONE 2.
•AT&L1
The analog adapter 2 has the higher priority to answer a voice or voice-band-analog-data call. If the analog adapter 2 is busy, the call is routed to the analog adapter, PHONE 1.
Multi Auto-Answering of Data Calls
When an ISDN data call comes in, the Model XM128 modem can determine the protocol to be used in one of two ways.
One is way is through the information conveyed by the setup message. For DSS1, this information includes the bearer capability, low-layer compatibility, or high-layer compatibility information elements; for 1TR6, it includes the Service Indicator as well as an Additional Octet of the Service Indicator.
The other way is by the Multi Auto-answering process. The Model XM128 modem determines the protocol by monitoring the B channel signal sent by the calling site.
With either method, the data call can be identified by the modem to be X.75, V.110, V.120, or PPP, MPPP Async-to-Sync conversion.
