I find some VOIP termination out there on the web and they have a very competive rate. I would love to buy their termination. But they use Mera Softswitch and Cisco 5300. So my question is can Asterisk connect to Mera Softswitch and Cisco 5300, so that I can call from my Asterisk box and termination call use their trunk?
is there something preventing you from asking the providers in question what protocols they support ?
failing that, 30 seconds spent on google would have given you a link to the Mera product mera-voip.com/files/mvts.pdf and you would have found that the Cisco 5300 would appear to support both SIP and H323.
so yes, it should be fine with Asterisk