Voice chat programs uses an Internet data stream. It isn't up to the developer of the application. No matter which app you find it will be limited based on your phone service provider and the type of phone you have.
Take a look at this (the protocols that are available via some services and phone types:
(taken from this thread, Can I talk and use Internet or other apps at the same time)
If you really want to know why and how this happens, without all the
techie speak - - - -
Verizon's 3G data and voice network is CDMA, and only a device with
SVDO technology can use voice and data at the same time (as opposed to
the current standard EVDO) on CDMA. The first device to do this was
the HTC Thunderbolt. The Galaxy S3 also has SVDO, so you can surf and
talk at the same time if you have Verizon 3G service.
The VZW iPhone does not have SVDO, so it can't do it. The iPhone on
ATT and Tmobile can do this, as those two carriers don't use CDMA -
they use GSM, which can do voice and data already. I don't know why
specifically, but just know that Tmo and ATT are GSM and Sprint and
VZW are CDMA.
Finally, any 4G LTE enabled phone on verizon can do talk and data at
the same time, as the data will run over the LTE network and the voice
runs over CDMA. So, devices like the Moto Droid Razr and other LTE
phones can do talk and data at the same time, but only if LTE service
is available. If in a 3G-only area, the Droid Razr can't do talk and
So if this is a needed feature you would have to shop for a specific phone provider and a specific phone that will allow you to use Data service and Phone service simultaneously... again, limited by the phone service and phone, not the app.