When doing local switching (hairpin), if the voice codec is G729 or some other DSP-intensive protocol, the NetPerformer:
• Disables the DSP
• Creates a TDM cross-connect scenario, and
• Initiates a pure 64 kbps PCM transfer.
The advantage of this method is the absence of compression, improved voice quality and no delays caused by echo cancellation. However, no call detail records are generated.
4.5.2 Using Overloaded MAP Entries Configuration
To configure a SIP Hairpin application with call detail records:
NOTE: The call detail records are managed by the SIP proxy server in this applica-tion.
1. Configure overloaded MAP entries with the IP address of the last MAP entry equivalent to the source IP address of the gateway. The last MAP entry can be of any type.
2. Configure either a DIALSTRING or DIALIP MAP entry to allow the NetPerformer to send an Invite to the SIP proxy server.
NOTE: The Invite must be sent to the SIP proxy server in order to generate a call detail record.
- If you configure a DIALSTRING entry, the MAP table will automatically use the Proxy server address as its destination.
- If you configure a DIALIP entry, you must set the destination IP address to the value of the Proxy server address.
NOTE: You must order the overloaded map entries correctly to ensure that the ingress call terminates on the same unit. For an example, refer to Scenario 1: Using Overloaded MAP Entries, below.
Call Setup
• When the SIP proxy server receives the Invite, it determines that the destination IP address is equivalent to the source IP address (the IPSRC address of the Net-Performer interface used to reach the destination IP address). The SIP proxy server then sends the Invite back to the source unit.
• The local NetPerformer extracts the voice codec used, the destination IP address and the telephone number (or DNIS) from the looped Invite.
• The local NetPerformer discovers that this is a local call, since the IP address retrieved from the Invite is identical to the source IP address of the unit.
• The NetPerformer retrieves the specific local voice channel number from the Egress hunt group ports parameter of this MAP entry, and completes the call to that port.
NOTE: The extracted voice codec must match the codec configured on the voice channel.
• As soon as a SIP egress call is transmitted across the SIP proxy server and termi-nates on the NetPerformer, a call detail record (CDR) is logged on the SIP proxy server database.
4.6 Example Applications
4.6.1 Scenario 1: Using Overloaded MAP Entries
In the application shown in Figure 4-1 on “SIP Hairpin Scenario 1” on page 4-2:
• The IP source address of the NetPerformer SIP VoIP is 172.168.1.10
• Overloaded MAP entries are used to perform the SIP Hairpin function.
Configuration
Here is how the overloaded MAP entries are set up:
DP/MAP
MAP> Entry digits (def:) ? 514
MAP 514.1> Map type...DIALSTRING MAP 514.1> Entry digits...514
MAP 514.1> Digits string length...10 MAP 514.1> Egress hunt group pattern...NONE MAP 514.1> Strip prefix number of digits...I0 E0 MAP 514.1> Ingress/Egress prepend string...NONE MAP 514.1> Ingress/Egress append string...NONE MAP 514.2> Map type...DIALIP MAP 514.2> Entry digits...514 MAP 514.2> Digits string length...10
MAP 514.2> Egress hunt group pattern...SEQUENTIAL MAP 514.2> Egress hunt group ports...101
MAP 514.2> Strip prefix number of digits...I0 E0 MAP 514.2> Ingress/Egress prepend string...I1 MAP 514.2> Ingress/Egress append string...NONE
MAP 514.2> Enter an IP address...176.168.1.10
NOTE: In this example, the Digits string length is set to 10 to include both a 3-digit speed dial number and up to 7 extended digits. If less than 7 extended digits are entered, the dial string is considered complete when global Dial timer parameter expires.
Call Setup
The order of the overloaded DIALSTRING entries demonstrates the order in which the
• The user dials the phone number 514-555-1212.
The NetPerformer detects a DIALSTRING Map type. It determines that the call is a real SIP call and sends the SIP signaling protocols to the SIP proxy server.
• If the voice connection cannot be established, the gateway interrogates the MAP service for another overloaded entry.
In this example, the NetPerformer detects a DIALIP Map type, and evaluates the ingress MAP IP address configured in the MAP entry.
• The ingress MAP IP address is identical to the source IP address of the gateway.
• The NetPerformer applies the MAP Ingress rules (in this case it prepends 1) to specify a long distance call across the public network. It also retrieves the MAP Egress Hunt group ports to cross-reference the MAP entry with the calling port.
4.6.2 Scenario 2: Bypassing the SIP Proxy Server
In this application scenario, we want to reach the MONTREAL area, which is area code 514. The MONTREAL area can be reached through:
• The SIP proxy server
• The local FXO channel (201), using MAP dialing rules
• The intermediary Unit 3, using MAP dialing rules. In this case, the SIP proxy server is bypassed.
Figure 4-2: SIP Hairpin Scenario 2: Bypassing the SIP Proxy Server
FXS: 101 Unit 1
Configuration
The MAP entries for this scenario are configured as follows:
DP/MAP
MAP> Entry digits (def:) ? 514
MAP 514.1> Map type...DIALSTRING MAP 514.1> Entry digits...514659 MAP 514.1> Digits string length...10 MAP 514.1> Egress hunt group pattern...NONE MAP 514.1> Strip prefix number of digits...I0 E0 MAP 514.1> Ingress/Egress prepend string...NONE MAP 514.1> Ingress/Egress append string...NONE MAP 514.2> Map type...DIALIP MAP 514.2> Entry digits...514659 MAP 514.2> Digits string length...10
MAP 514.2> Egress hunt group pattern...SEQUENTIAL MAP 514.2> Egress hunt group ports...201
MAP 514.2> Strip prefix number of digits...I0 E0 MAP 514.2> Ingress/Egress prepend string...I1 MAP 514.2> Ingress/Egress append string...NONE
MAP 514.2> Enter an IP address...165.30.30.10 MAP 514.3> Map type...DIALIP MAP 514.3> Entry digits...514659 MAP 514.3> Digits string length...10 MAP 514.3> Egress hunt group pattern...NONE MAP 514.3> Strip prefix number of digits...I0 E0 MAP 514.2> Ingress/Egress prepend string...I1 MAP 514.2> Ingress/Egress append string...NONE
MAP 514.3> Enter an IP address...190.40.40.10