I'm using an SMS sending service provided by a local mobile carrier. The carrier enforces clients to connect to their datacentre over a VPN in order to reach their endpoints. The VPN tunnel must always be kept open (i.e. not on demand).
Currently, I'm using a micro EC2 instance that acts as middleware between my main production server (also an EC2 instance) and the carrier endpoint.
Production Server --> My SMS Server --over VPN--> Carrier SMS Server
Is there a way to replace my middleware server with an AWS Lambda function that sends HTTP requests to the carrier over an always-on VPN tunnel?
Also, can an AWS Lambda function maintain a static IP? The carrier has to place my IP in their whitelist before I can use their service.