Unlimited sip provider

So, I have been tasked with finding a sip-pstn gateway provider on the cheap, who can provide unlimited calls over 4 channels. I know this isn’t the best way to do it, but it’s what management wants.

So, my question is, does anyone out there have any experience with or suggestions of providers who can provide 4 sip channels, w/ an unlimited minute plan, and local DIDs?


P.S. - Broadvoice is not an option. Never again.