Which protocol is responsible for media control between IMS-MGW and P-CSCF?

Interview
1

Q. Which protocol is responsible for media control between IMS-MGW and P-CSCF?

a) GTP
b) SDP
c) MGCP
d) MEGACO (H.248)

Check 🔎

:arrow_right: Correct answer: Letter d.

MEGACO (H.248) is the protocol used for media gateway control between the IMS Media Gateway (IMS-MGW) and the P-CSCF (Proxy Call Session Control Function), or more generally, the Media Gateway Controller (MGC). It provides the signaling mechanism to manage bearer paths, codec control, and media stream handling.

Option Analysis:

a) :x: GTP
→ Incorrect. GPRS Tunneling Protocol is used for user-plane IP packet transport between eNodeB, SGW, and PGW — not for media control.

b) :x: SDP
→ Incorrect. Session Description Protocol is used within SIP messages to describe media formats and capabilities, but it’s not used for control of the media gateway.

c) :x: MGCP
→ Incorrect. Media Gateway Control Protocol is an older protocol, mainly used in non-IMS PSTN-IP interconnects. IMS architectures prefer MEGACO/H.248.

d) :white_check_mark: MEGACO (H.248)
→ Correct. It is the standard used for controlling media gateways in 3GPP IMS-based networks.