For redundancy, you always need at least two SIP Trunks, preferably with different providers. That way if one provider fails the edge rolls to the next.
Same thing for the internet connection. Two different connections with different ISPs for full redundancy.
No way to place outbound calls if your sole SIP trunking provider goes down.
If it's just the port on the edge that fails, you should have redundant edges and the calls will fail over to another edge (or should), and you might be able to switch the trunk connection to a different port on the same edge (though it's not likely just one port will fail).
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George Ganahl CCXP, GCA
Principal Technology Consultant
Genesys
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