In this blog we are going to look into how a Linksys PAP2 Voice Adapter can be used to make free calls from one device to another over the internet or intranet.

Prerequisites

This scheme can be implemented if you have offices in 2 or more locations and you want to enable calls from one office to another. The prerequisites for this is that you must have either Public ip address at both locations or you must be on the same intranet, either through VPN or through Leased lines. Prior to enabling VOIP, you must ensure that your ISP has not blocked VOIP as well as the VOIP ports are open on the Firewall.

VOIP Ports

SIP

Source port range:5060 to 6081
Destination Port range:5060 to 6081
Source IP Address:IP Address of the VOIP device
Destination IP Address:ip address of the peer device

RTP

Source port range:16384 to 16482
Destination Port range:1024 to 65535
Source IP Address:IP Address of the VOIP device
Destination IP Address:any IP Address

Configuration

We will take an example while configuring the devices. The device in Mumbai is device A and the device in Kuwait is device B. The ip address of the device in Mumbai is 192.168.1.50 and the ip address of the device in Kuwait is 192.168.1.51. (Note: The ip addresses can be anything as long as they reach each other)

Configure these parameters in device A:
– Line 1 tab, SIP Settings section set SIP port: 5060.
– Line 2 tab, SIP Settings section set SIP port: 5061.
– In Line 1 and Line 2 tabs, Proxy and Registration section all fields blank or NO except Make Call Without Reg: YES and Ans Call Without Reg: YES.
– In Line 1 tab, Subscriber Information section set Display Name: <what you want to be displayed when you call>, User ID: 11 and leave other fields emply.
– In Line 2 tab, Subscriber Information section set Display Name: <what you want to be displayed when you call>, User ID: 12 and leave other fields emply.
– In Line 1 and Line 2 tabs Dial plan section Dial Plan field set (21S0<:@192.168.1.51:5060>|22S0<:@192.168.1.51:5061>), Enable IP Dialing: YES

Configure these parameters in device B:
– Line 1 tab, SIP Settings section set SIP port: 5060.
– Line 2 tab, SIP Settings section set SIP port: 5061.
– In Line 1 and Line 2 tabs, Proxy and Registration section all fields blank or NO except Make Call Without Reg: YES and Ans Call Without Reg: YES.
– In Line 1 tab, Subscriber Information section set Display Name: <what you want to be displayed when you call>, User ID: 21 and leave other fields emply.
– In Line 2 tab, Subscriber Information section set Display Name: <what you want to be displayed when you call>, User ID: 22 and leave other fields emply.
– In Line 1 and Line 2 tabs Dial plan section Dial Plan field set (11S0<:@192.168.1.50:5060>|12S0<:@192.168.1.50:5061>), Enable IP Dialing: YES

Now, how it works:
– To call device A Line 1 from device B (any line) dial 11.
– To call device A Line 2 from device B (any line) dial 12.
– To call device B Line 1 from device A (any line) dial 21.
– To call device B Line 2 from device A (any line) dial 22.

I hope my post has been helpful in your life but the only guide which can help you in the hereafter is the Qur’an. You can download the English translation of the Qur’an here.