PBX can be used to make and receive calls from Toplink
accounts. This page describes how a trunk should be configured in order to minimize the time to set up a Toplink trunk.
Toplink seems to use some kind of session border controller, in the version that we used for documenting the setup, they are sending four zero packets back to the user agents if they determine that this user agent seems to be behind NAT. This mechanism works in most environments, however some routers do not accept outside traffic for refreshing NAT bindings.
Toplink customers must register their accounts at toplink, therefore the register trunking mode must be used. A sample setup looks like this:
Type: SIP Registration
Display Name: Test Customer
Password (repeat): XXXXXXXX
Outbound Proxy: toplink-voice.de
Is Secure: yes
Strict RTP Routing: off
Failover Behavior: No failover
The Extension can be set to a simple account (e.g. auto attendant), but because in Europe direct inward dialling is easy, the PBX will probably extract the extension number right out of the SIP packet. In order to do this, the extension should be a pattern like shown in the example, where the PBX will match the international number prefix provided by toplink and use only the extra digits to locate the account. The default account will be 0, in case that the number should not be available on this system.
The prefix parameter is used to convert the PBX number into a global telephone number and is used for outgoing calls.
Toplink does not support secure calls. If you want to initiate secure calls, you need to check if the route between the PBX can be attacked by eavesdroppers. If you have doubts, you better turn the flags to off.