A system to provide second generation (2G) voice services over internet protocol, the system including: a voice gateway (VGW) including a 2G stack to communicate control plane information and user plane information with a 2G user terminal (UT) via a circuit-switched network without modifications to the 2G-UT, an Iu-CS IP stack, and a relay to map the control plane information between the 2G stack and the Iu-CS IP stack, and vice-versa; a mobile switching center (MSC), connected to the VGW via the Iu-CS IP stack, to manage and establish the voice services between the 2G-UT and a public switched telephone network (PSTN) based on the mapped control plane information; and a media gateway (MGW) connected to the VGW via the Iu-CS IP stack, where the MGW communicates the user plane information between the 2G-UT and the PSTN after the MSC 2-G UT vocoder, e.g. AMBE, has established voice services.