Asterisk

It is often useful to be able to determine the state of the devices that are attached to a telephone system. For example, a receptionist might require the ability to see the statuses of everyone in the office in order to determine whether somebody can take a phone call. Asterisk itself needs this same information. … Read more

ISN, ITAD, and freenum.org The biggest shortcoming of ENUM is that it uses a numbering system that is not under the control of any Internet numbering authorities. The freenum.org project solves this problem by utilizing a numbering scheme that is managed by IANA. This means that a formal, globally valid, nongeographic numbering system for VoIP … Read more

One of the attractions of VoIP is the concept of avoiding the use of the PSTN altogether, and routing all calls directly between endpoints using the Internet at little or no cost. While the technology to do this has been around for some time, the reality is that most phone calls still cost money—even those … Read more

In Asterisk, these two functionalities are exclusive to one another, and can be used independently of one another. Some businesses that contain large warehouses, or have employees who move around the office a lot and don’t necessarily sit at a desk all day, utilize the paging and parking functionality of their systems to direct calls … Read more

Using the Asterisk Database (AstDB) Asterisk provides a powerful mechanism for storing values called the Asterisk database (AstDB). The AstDB provides a simple way to store data for use within your dialplan. The Asterisk database stores its data in groupings called families, with values identified by keys. Within a family, a key may be used … Read more

Expressions and Variable Manipulation As we begin our dive into the deeper aspects of dialplans, it is time to introduce you to a few tools that will greatly add to the power you can exercise in your dialplan. These constructs add incredible intelligence to your dialplan by enabling it to make decisions based on different … Read more

Telephony is one of those areas of life where, whether at home or at work, people do not like surprises. When people use phones, anything outside of the norm is an expect‐ ation not met, and as someone who is probably in the business of supplying telephone systems, you will know that expectations going unmet … Read more

Storage Backends The storage of messages on traditional voicemail systems has always tended to be overly complicated.  Asterisk, on the other hand, not only provides you with a simple, logical, filesystem-based storage mechanism, but also offers a few extra message storage options. Linux Filesystem By default, Asterisk stores voice messages in the spool folder, at … Read more

VoIP Compared to the vast history of telecom, VoIP is still a relatively new concept. For the century or so prior to VoIP, the only way to connect your site to the PSTN was through the use of circuits provided for that purpose by your local telephone company. VoIP now allows for connections between endpoints … Read more