Best voip option for slow speeds
I'm looking into voip options for my cell phone while travelling. The biggest criteria is that it has to work even when internet speeds (e.g., wifi in hotels, 3G) are not that great. I already have account with Fongo (Dell Voice) and FreePhoneLine, so I know I can just purchase configuration files for either one of them (probably FPL because I already have an ATA device). I know voip.ms is often highly recommended, but I'd rather have a free permanent DID number (instead of paying for it every month regardless of whether I need it or not). However, if it will be the most reliable under less than ideal circumstances, then I'd definitely consider it. Skype is out as it doesn't allow me to have a Canadian number. Am I missing any other options? Thanks.