Asterisk - OpenSER - ITSP setup

Asterisk Asterisk Support
1

Hi,
we want to setup an Asterisk service for multiple clients with 1 SIP trunk to our ITSP/PSTN provider.

We want to put OpenSER as front end and multiple Asterisk servers to handle the load for all the clients. We have 1 SIP trunk to our ITSP/PSTN provider.

How/where do we interconnect to out PSTN/ITSP provider? On the front-end OpenSER or do we need an OpenSER on the backend only for the SIP trunk?

How good is OpenSER with NAT?

2

OpenSer or SER both have good nat traversl support.

3

can you tell/advise me if we only need a frontend OpenSER server, or also 1 for the connection to our PSTN/ITSP provider?