Asterisk Interview Questions & Answers (2025)

Asterisk is one of the open source frameworks that is essentially used for the construction of different communication applications.

The software Asterisk was popularized by the company Digium created by Mark Spencer. It has gained its immense popularity in the year 2007 even though it was available in the market since 1999.

Asterisk is one of the largest open source communicating software that can accommodate over 10000 phones.

One of the most essential reasons for using PBX platform with Asterisk is because it saves time and gives immense support to tech savvies. When PBX platform is used alongside with Asterisk, over time it ensures that the system is well maintained and can be continuously updated without the requirement of any kind of modification.

The minimum components required to set up Asterisk are:

• Compatible server
• WAN cards
• Phone adapters
• Asterisk compatible VoIP phones
• Network

In order to search for Asterisk mailing list archives, different ways followed are:

• Using search engine at VoIP forums
• Mail - archive can also provide Asterisk mailing list achieves
• GMANE search
• Google search

In order to start Asterisk running in no time, firstly do not start with any kind of bells or whistles. Then follow the quick-start guide and once you have Asterisk running, you can add in the hardware and different features.

Operating the Asterisk software behind the NAT firewall purely depends on the protocol. To make sure that you can run Asterisk behind NAT firewall, first of all, make sure that the default principle with NAT has no device from the outside and that it can contact with something on the inside as well.

Converting and creating sound files using Asterisk can be carried out using the Asterisk cmd record application.

Different echoes can be eliminated using the echo=no switch that is available with Asterisk. You could also use a wide range of variables provided with Asterisk in order to resolve the local problem and also find the real source of the problem.

Yes. Asterisk can be used without any kind of special hardware. Unlike other software, hardware such as ISDN cards and adapters are not a mandatory requirement. It also works exceptionally well as a VoIP and voicemail server in collaboration with IAX, SIP, MGCP and H.323 application without the need for external PSTN connectivity.

No. Asterisk is not a complete SIP Proxy Server. It is a SIP client that connects it to other SIP Proxies. It is also a very good SIP Server that allows other SIP clients to connect and work with Asterisk and receive calls. It also allows the clients to set up and transfer calls in addition to participating in conferences.

Asterisk can be operated with only single SIP registration such as Asterisk config sip.conf. If an operator wants to utilize more than one SIP registration then he needs to add additional peers and change the dial plan so as to be able to call more devices while calling multiple callers with user’s extension. The syntax general used with this respect include is: dial (SIP/BrianPhone1&SIP/BrainPhone2)

In order to implement H.323 with Asterisk, the following can be used:

asterisk – oh323

asterisk – h323

In order to connect Asterisk PBX with various VoIP Service Provider, different supports are utilized. Some of the commonly used supports include SIP, IAX, H.323, etc.

Asterisk got its name from the symbol (*) that is widely used in the Unix commands.

Yes. Asterisk can be operated with multiple synchronized PSTN incoming calls. In order to carry out this operation one needs to have a Primary Rate Interface line that is initially enabled with PSTN service provider. After which, if a caller wants to use the PSTN line, then no other caller will be allowed to use the same line. Therefore, the new caller will be assigned a new line or will be answered with a busy tone or any other kind of waiting tone that has been subscribed to by the PSTN provider. After the PRI lines are subscribed, Asterisk software can be installed so to provide multiple communication services.