Here are the added IPBX2027 steps I found to get the old disabled & the new two PJSIP trunks laid down/operational:

1) Disable old SIP Skeytel trunks

2) Add the following to the "/usr/local/sbin/iptables-custom" …

/usr/sbin/iptables -A INPUT -s 35.85.225.96 -j ACCEPT
/usr/sbin/iptables -A INPUT -s 3.99.65.224 -j ACCEPT
/usr/sbin/iptables -A INPUT -s 3.101.177.224 -j ACCEPT
/usr/sbin/iptables -A INPUT -s 44.199.94.192 -j ACCEPT
/usr/sbin/iptables -A INPUT -s 35.215.45.65 -j ACCEPT
/usr/sbin/iptables -A INPUT -s 35.209.126.210 -j ACCEPT
/usr/sbin/iptables -A INPUT -s 35.212.222.157 -j ACCEPT

3) "iptables-restart"

4) If you have a hardware firewall with say whitelisting, be sure to add these subnets & IP’s there as well of course.

5) Follow Skyetel’s FreePBX PJSIP trunk directions:

INBOUND: https://support.skyetel.com/hc/en-us/articles/4410765264791-FreePBX-13-Create-Inbound-Trunk

OUTBOUND North America: https://support.skyetel.com/hc/en-us/articles/4410672050967-FreePBX-13-Create-Outbound-Trunk-for-North-America

6) Create or change your Skyetel "IP Authentication -> IP Group" entry to use 5061 rather than 5060 to connect

That’s it, and only two trunks using latest Skyetel infrastructure.

[WM: What you need is an Analog Telephone Adapter. Google is your friend. Or visit voip-info.org forum for suggestions.]