Call processing occurs in different ways depending on the type of endpoint and trunk that is used.
XNET
Compression
IP Telephone to IP Trunk
Non-IP Telephone/Trunk to IP Trunk
IP Trunk to IP Telephone
IP Trunk to Non-IP Telephone
IP Trunk to IP Trunk.
XNET reuses existing call processing for leased-line DPNSS. The extra software necessary to set up and synchronize the B-channel calls is transparent to the call itself.
Trunk profiles are used to specify the desired trunk service and interconnect restrictions for XNET calls (especially useful for Release Link Trunks). The local profile defines the trunk service characteristics for outgoing calls. The remote profile defines the trunk service characteristics for the terminating system using the same profile number as the outgoing remote profile at the Local system. Different calls between the same pair of systems can have different profiles. This is achieved by programming different routes in the ARS Routes form and different XNET trunk groups (which in turn specify different XNET trunk profiles) in the IP/XNET Trunk Groups form.
Users receiving XNET calls should not detect any significant difference from leased-line DPNSS. Occasionally a local DPNSS trunk number and/or label is displayed if the calling number, name, or trunk ID information is not available. Within leased-line DPNSS, the trunk information is that of the DPNSS trunk on which the call is received. Within XNET, the XNET trunk label is used for this purpose. When there are no voice channels available to establish a call, the processing is equivalent to a lack of channels on leased-line DPNSS.
Compression allows calls to be made utilizing less bandwidth than an uncompressed call. Compression is used only when programmed by the administrator. Higher quality uncompressed audio is used by default.
See IP Networking/XNET Compression for details.
When a call is made from an IP telephone to another IP telephone on a remote 3300 ICP, ARS programming instructs the system to use an IP route. The destination IP telephone rings and ringback tone is given to the originator of the call. When the called party answers, the system streams voice packets from the originator to the endpoint.
If the endpoint (after all call forwarding) is busy, or the route is congested and no other routes are available, the system plays busy tone to the originator. If the telephone has a display, an appropriate message may be displayed as it would for a leased line DPNSS call.
If a destination system is unreachable after alternative routes have been tried, the originator is given reorder tone.
When digits are received from a non-IP telephone or trunk and ARS programming instructs the system to use an IP route, the destination telephone rings and ringback tone is given to the originator. When the called party answers, the non-IP telephone is connected by a TDM to IP resource to stream voice packets to the destination. If there is no TDM to IP resource available, reorder tone is played to both the called and calling parties.
If the endpoint (after call forwarding) is busy, or the route is congested and no other alternative is available, the caller receives busy tone.
If the destination system is unreachable, reorder tone is given to the caller.
When a call is received over an IP trunk, the digits are used in conjunction with forwarding and grouping configurations to determine which IP telephones should receive the call. When the call is answered, the terminating system streams voice packets to the originator.
After the call is connected, the IP endpoints stream the voice signals directly to each other.
