Case Studies

[aa-local] ignorepat => 9

exten => _9NXXXXXX,1,Goto(trunkdial,${EXTEN},1) exten => _91800XXXXXXX,1,Goto(trunkdial,${EXTEN},1) exten => _91866XXXXXXX,1,Goto(trunkdial,${EXTEN},1) exten => _91877XXXXXXX,1,Goto(trunkdial,${EXTEN},1) exten => _91888XXXXXXX,1,Goto(trunkdial,${EXTEN},1) include => aa

[aa-ld] ignorepad => 9

exten => _91NXXNXXXXXX,1,Goto(trunkdial,${EXTEN},1) include => aa-local

[trunkdial]

exten => _9.,1,Dial(${TRUNK}/${EXTEN:${TRUNKMSD}}) exten => _9.,2,Congestion(5)

exten => _9.,3,Hangup

Here we used the same trunkdial context as in the previous example for exactly the same reasons. However, with all these different outgoing contexts, the complexity of adding extensions would simply keep increasing.

Each company has a unique set of outgoing contexts so that only its extensions are included. This helps ensure the correct extension is reached when extensions exist in more than one context, such as extension 100 existing in contexts aa and al.

Compared to our previous example, the system offers fewer features for our users: we do not have conferences, we cannot get to the directory, and we must call our own extension and press the * key to get to our voicemail. However, these features can be activated at will, or even as customers pay to have them added.

Conclusions

Asterisk has again been used to fulfill a different need in a phone system. By taking advantage of contexts, we have been able to create multiple virtual phone servers with only one server, one PRI line, and one set of configuration files.

Summary

In looking at these case studies, I hope you have been able to spot common features in what we are trying to implement in each different situation. We can learn from these implementations and apply many of the same strategies when we encounter users with similar needs.

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