Small-form-factor server?

Hello

I’d like to provide SOHO’s with an Asterisk-based IVR + CRM. To keep things tidy, I prefer to use PCI cards. The server will typically be used to handle a single POTS line, by up to 10 employees, so there’s no need for a really fast CPU.

Before I try to build my own, are there brands/models you would recommend? I’d like something as small and silent as possible?

Shuttle’s X27 or MSI’s NetTop don’t have room for a PCI card, but this is the type of hardware I’m looking for.

Thank you for any hint.