Cisco Systems WRP400 Manual Do Utilizador

SIP Trunking and Hunt Groups on the SPA8000

ATA Administration Guide

80

Although the figure shows only one ITSP account, each standalone line and each 
Trunk Group can be configured with a different ITSP (with some limitations applied).

The ITSP may set a limit to the number of calls that can be made on a trunk group. 
You can configure a trunk group’s call capacity parameter to meet the 
requirements of the ITSP. Both incoming call and outgoing calls are counted 
towards this limit. The call capacity has the following impact on call handling:

•

Inbound calls: When the limit is reached, the Trunk UA replies 486 to the 
caller. 

•

Outbound calls: When the limit is reached, the Line UA plays a fast busy 
tone to the caller. Note that a trunk line can make an outgoing call only 
through its own trunk. If that trunk reaches full capacity, it will not attempt to 
failover to use other trunks.

You can configure this setting in the Voice tab > Trunk (T1 ... T4) page, Subscriber 
Information section, Call Capacity field. For more information, see 

An incoming call is handled as follows: 

When an incoming call is detected by the Trunk UA, the UA first checks if there is 
capacity to handle the call. If there is insufficient capacity, the UA rejects the call 
with a 486 response. 

If there is spare call capacity, the UA consults the Contact List to determine which 
line or lines to ring (that is, for the proxy to send SIP INVITE to), and starts “hunting.” 
(See 

)

When a line is selected to ring, one or more PBX phones may be alerted, according 
to the PBX features and configuration. 

The Caller ID of the external Caller is signaled by the Line UA out to the FXS port 
using the configured Caller ID method (FSK, DTMF, etc.). The PBX must be able to 
detect Caller ID signal in order for the proper Caller ID to show.