An ISDN serial interface configured for integrated mode supports data and voice calls using incoming call type checking to accept incoming voice and data calls when an inbound voice dial peer is matched.
The call type of an incoming call is determined using the incoming dial-peer. For data dial peer matching, the called number of an incoming call is used to match the incoming called-number of POTS dial peers.
Enabling integrated services allows data and voice call traffic to occur from ISDN PRI interfaces simultaneously.
When an interface is in integrated service mode:
- ISDN performs calltype checking for the incoming call. The call is rejected by ISDN if no voice or data dial peer is matched for an incoming call.
- The voice option for the isdn incoming-voice command, which treats incoming calls as voice calls, is not available.
By default, the integrated service option is disabled from the supported interfaces.
After an ISDN interface is assigned to a trunk group, you can configure maximum incoming and outgoing calls based on the call type (voice or data) or direction (inbound or outbound) through the trunk group.
When the isdn integrate calltype allcommand is removed from the interface, the isdn incoming-voice voicesetting is restored and the interface returns to voice mode.
This feature adds support for multilevel precedence and preemption (MLPP) for dial-on-demand routing (DDR) backup calls over outgoing voice calls.
Precedence designates the priority level that is associated with a call. Preemption designates the process of terminating lower-precedence calls so that a call of higher precedence can be extended. DDR backup is used to provide backup to a WAN link using any DDR or a dial-capable interface, like ISDN PRI interfaces.
From the gateway, voice and DDR backup calls are controlled by different entities.
- The preemption level of an outgoing voice call is determined using the selected outbound POTS dial peer.
- The preemption level of a DDR backup call is determined using the dialer map class.
A DDR backup call with higher precedence preempts the active outgoing voice call with a lower precedence if the idle B channel is not available from a trunk group during the DDR backup call setup. If MLPP is not configured, data calls wait for a free channel.
A trunk group is used as a common channel resource pool for idle channel allocation for outgoing voice calls and DDR backup calls. Multiple ISDN PRI interfaces that have been configured for integrated services are assigned to this trunk group to build up a channel resource pool for both voice and data calls. Enabling preemption on the trunk group allows DDR call preemption over a voice call per trunk group.
The tone timer defines the expiry timer for the preemption tone for the outgoing voice call, which is being preempted by a DDR backup call. When the tone timer expires, the call is disconnected.
During dial-on-demand routing (DDR) call setup, an idle B channel is selected from the trunk group. The trunk group and preemption level are configured as part of a map class, which can be attached to a dialer map or dialer string. By default, the preemption level of dialer calls is set to the lowest level (routine) to disable the MLPP service for a DDR call.
The trunk group preemption level is configured as part of a map class, which can be attached to a dialer map or dialer string.
- For legacy DDR, configure the dialer interface to associate the class parameter with the dialer in-band and dialer map commands.
- For dialer profiles, configure the dialer interface to associate the class parameter with the dialer pool and dialer string commands.
For TDM-only calls, or for calls that are hairpinned, the preemption tone is not heard as the DSPs are dropped. For this reason, you must disable TDM hairpinning on the voice card to use the MLPP DDR backup call preemption feature.
The preemption level of an outgoing voice call is defined from the outbound POTS dial peer. The preemption level defines the preemption priority level of an outgoing voice call.
ISDN call failures are most commonly attributed to dial-on-demand routing (DDR), ISDN layers 1, 2, and 3, and Point-to-Point Protocol (PPP), including link control protocol (LCP), Authentication, or IP Control Protocol (IPCP)-related issues.