Integrate with Elavon
ELAVON is a US payment gateway which is pretty famous. It would be nice if Zoho Subscriptions is integrated with it.
Corey Moullas commented
I know this is old but in case anybody comes across this in the future this is already possible. If you have a merchant account with most anybody, you can use Authorize.net as your gateway and they will plug into your merchant account. There are additional monthly fees for Authorize.net but it's already integrated with Zoho so it's possible to use almost any merchant account you want this way.