How To Get Mobile Phone Calls From Home When You Are Overseas, Without Roaming

Jen and I have prepaid mobile phone accounts which don't have international roaming. The problem we will face when we go overseas is that the phones won't get SMS (text) or phone calls at all. The solution to calls is to use the settings in your phone to divert the incoming calls to a special VOIP landline number. This special number is able to be installed on your mobile phone with an app called Zoiper which uses internet data to recieve and make calls. So if you have a local sim with data or access to wifi, you can have your calls diverted to your phone whilst overseas.
If yo don't answer or have no signal the caller gets switched to voicemail which is recorded and sent to your email address. Magic! Call them back on their landline for 10c or 15c a minute to their mobile. Cheap and works a treat.
SMS is still a problem. Any clues what we can do for that?

Music: purple-planet.com/