1. Detect which OS/arch you are using.

• Find distribution.
• cat /etc/redhat-release : This command will give you an output like:
  Red Hat Enterprise Linux Server release 7.0 (Maipo)
  Fedora release 21 (Twenty One)
• Find architecture.
• uname -m : This command will give you an output like x86_64 or i686.

• Install the repository RPM.
• Download corresponding repository RPM from "Repository RPMs" page.
• Install the repo RPM. For example, if you downloaded OpenSIPS 2.4 repository RPM for EL7 x86_64, here is the command:
  yum localinstall opensips-yum-releases-2.4-1.el7.noarch.rpm
  (or rpm -i instead of yum localinstall for old distributives)
• As alternative, you can install the package directly by using the repository RPM URL:
  yum install https://yum.opensips.org/2.4/releases/el/7/x86_64/opensips-yum-releases-2.4-1.el7.noarch.rpm
  (or rpm -i instead of yum install for old distributives)

• Install and start the OpenSIPS server.
• Now, you can install OpenSIPS with single command:
  yum install opensips
• Start the OpenSIPS server:
  systemctl start opensips - for systemd distributives
  service opensips start - for old distributives
• If you want to start the OpenSIPS server every time on boot, run this:
  systemctl enable opensips - for systemd distributives
  chkconfig opensips on - for old distributives