Install Asterisk from a repository

Ubuntu features a software repository that includes Asterisk. A software repository can be thought of as a database of application installation packages that can be installed on your system using just a command or two. In Ubuntu and other Debian-based distribution, software (such as Asterisk) is installed, upgraded, or removed using the apt-get command. 

Here are the steps to install Asterisk on Ubuntu from a repository:
1. First, run the sudo apt-get update && apt-get upgrade command to obtain the latest information about the packages available from the repository and upgrade all installed packages:

bob@ubuntu:~$ sudo apt-get update && apt-get upgrade

2. After the system has been updated, run the sudo apt-get install asterisk command to install Asterisk on your system:

bob@ubuntu:~$ sudo apt-get install asterisk
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
asterisk-config asterisk-core-sounds-en asterisk-core-sounds-en-gsm
asterisk-modules asterisk-moh-opsound-gsm asterisk-voicemail freetds-common
libfreeradius-client2 libgsm1 libiksemel3 liblua5.1-0 libodbc1
libopencore-amrnb0 libopencore-amrwb0 libpj2 libpjlib-util2 libpjnath2
libpq5 libresample1 libsox-fmt-alsa libsox-fmt-base libsox2 libspandsp2
libsqlite0 libsrtp0 libsybdb5 sox
Suggested packages:
asterisk-doc asterisk-dev asterisk-ooh323 asterisk-dahdi asterisk-vpb
libmyodbc odbc-postgresql tdsodbc unixodbc-bin libsox-fmt-all srtp-utils
The following NEW packages will be installed:
asterisk asterisk-config asterisk-core-sounds-en asterisk-core-sounds-en-gsm
asterisk-modules asterisk-moh-opsound-gsm asterisk-voicemail freetds-common
libfreeradius-client2 libgsm1 libiksemel3 liblua5.1-0 libodbc1
libopencore-amrnb0 libopencore-amrwb0 libpj2 libpjlib-util2 libpjnath2
libpq5 libresample1 libsox-fmt-alsa libsox-fmt-base libsox2 libspandsp2
libsqlite0 libsrtp0 libsybdb5 sox
0 upgraded, 28 newly installed, 0 to remove and 717 not upgraded.
Need to get 8,810 kB of archives.
After this operation, 22.1 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y

Press Y when prompted for a selection. Asterisk should be downloaded and installed in a couple of minutes.