I have recently installed Asterisk 10.x and I am unable to bring up
my SIP trunks or register SIP phones. How can verify if the service SIP is running?
Did you disable the firewall (iptables) on your server?
First you need to check if chan_sip.so is loaded. You can do this by running “module show” command in Asterisk CLI.
If the module is loaded, you have a lot of sip debug commands in the Asterisk CLI. I will let you discover them by yourself 