You need to properly formalate the task you want to achive and select the right tools for that. Software developers do not use desktop applications like Ekiga for their projects. It's just because desktop applications are written for the users, they are not for software developers. You can only modify desktop applications like Ekiga in the source code, but that is a whole different story.
If you want to have a VOIP endpoint and connect it to a speech recognition service, you need to look on IVR systems and similar things. IVR system is a specific tool to implement complex interactions over the VOIP protocols. Some examples are:
Freeswitch
Asterisk
GNU Gatekeeper - a project is built on the same Opal technology as Ekiga
You can setup freeswitch to wait for the calls and pass them to the pcoketsphinx. You can do the same with Asterisk. For more details see
How to use Pocketpshinx from Freeswitch
How to integrate Pocketsphinx in Asterisk using UniMRCP project