Choosing between Host Based Routing and SIP Registration

MiRTA PBX doesn't support natively SIP registration for Providers, but you can manually configure them in sip.conf and then reference them in the Admin/Providers section.

Here a simple example about a static registration in sip.conf

[general]
...
register => 49088751:cyj74rrjd8gg@sip.flowroute.com

[flowroute]
type=friend
secret=cyj74rrjd8gg
defaultuser=49088751
username=49088751
fromuser=49088751
host=sip.flowroute.com
dtmfmode=rfc2833
context=fromoutside
canreinvite=yes
allow=ulaw
allow=alaw
allow=gsm
insecure=port,invite
fromdomain=sip.flowroute.com

In the web interface, you'll reference the tag in square brackets [flowroute]

Once sip.conf has been edited, to have it working, doing a sip reload is needed. Take in mind doing a sip reload will trash all clients registrations. Phones will be unavailable until new registration.

Before choosing to go with the SIP registration, please take the time to read

https://blog.flowroute.com/2014/07/09/sip-registration-vs-host-based-routing-which-side-wins/