Page 2Hardware ConsiderationsEach VoIP PCB must be associated with a VoIP PCB at another i-Series site. There must be a dedicated one-to-one relationship betweenthe VoIP PCBs across the network. For example, if a remote site has 2 VoIP PCBs, the main office must also have 2 PCBs for sendingand receiving VoIP calls to that site. Outgoing calls on a VoIP PCB must be routed only to the IP address of the associated VoIP PCB atthe remote site.This is done to emulate the point-to-point connection provided by a T1 or PRI trunk. With this configuration, if all ports on the localPCB are busy, then all ports on the associated remote VoIP PCB will also be busy. This is required in a system with multiple VoIPPCBs to force overflow of outgoing calls to an alternate route (another VoIP PCB) if all ports at the remote site are busy.Programming ConsiderationsEach VoIP PCB must be assigned to its own trunk group in Program 0905 - Trunk Groups. All ports on a VoIP PCB must be assignedto the same trunk group.When multiple VoIP PCBs are installed at a site, ARS or F-Route must be set up with alternate routes with each route sending calls to adifferent outgoing trunk group (VoIP PCB). Outgoing calls to a particular VoIP PCB must use only the IP address of the associated VoIPPCB at the remote site.It is recommended that the hunting order (the order of the alternate route selection) be reversed at each site to reduce the chance of callcollisions.Outgoing Calls — If Using a GatekeeperIf a Gatekeeper is used, the 124i Enhanced must be programmed to use the Gatekeeper. All user-dialed digits for a VoIP call are sent tothe Gatekeeper which will set up and manage the call.Some Gatekeepers accept overlap dial information - some do not. The 124i Enhanced system can enable either Overlap or En BlocSending for each VoIP PCB (Program 0319 Item 1). This results in differences in the operation of outgoing calls. Overlap SendingEach time a user dials a digit, the dial information is sent to the Gatekeeper. This operation is just like using an analogtrunk. En Bloc SendingDial information must be stored and then sent all at once. After dialing the digits for an outgoing call, the user must waitfor the inter-digit timer to expire before the digits are sent. The user may, however, press the # key to send the dialed digitsbefore the timer expires.Outgoing Calls — If Not Using a GatekeeperA user is not allowed to seize the VoIP trunk manually because dialed digits cannot be sent directly to the VoIP trunk. An IP addressmust be provided to route the call. This means that a user cannot press a trunk key or dial a trunk access code to seize a VoIP trunk.To determine the destination IP address from the dialed digits, the 124i Enhanced system uses F-Route or ARS. These programs havebeen modified to support VoIP. The following description shows how to determine an IP address.How to Determine the Destination IP Address Using ARS or F-RouteThis option must be used for reaching destinations such as a key telephone at a remote system without a Gatekeeper. The target destina-tion will be specified by a local trunk group number, an IP address and the called party number.