The IP-SM-GW is a sub mode of Next-Gen Messaging Center — the function that lets an IMS subscriber on SIP exchange messages with a 2G handset on MAP. Turn it on, and VoLTE messaging works from day one.
When you launch VoLTE, IMS-registered subscribers send messages over SIP. Legacy 2G/3G subscribers and external systems use MAP. The two protocols do not understand each other.
An IMS subscriber sending an SMS to a legacy handset fails silently if nothing translates between SIP and MAP. At launch this affects most of the network — every message to a contact not yet on LTE.
Two protocols, one boundary
The IP-SM-GW is a sub function of the Ouroboros Next-Gen Messaging Center in a standalone product.
Translate, deliver, route back
When an IMS subscriber sends a message, the platform receives it over SIP, converts it to the SMS format, and delivers it over MAP in real time. Messages from legacy subscribers route back to the IMS subscriber's SIP client. The translation is invisible to both ends — neither subscriber knows the other is on a different generation. Delivery and read receipts pass in both directions.
VoLTE day one, roaming interworking, A2P to IMS, MVNO bridges — the translation layer.
VoLTE launch — interoperability from day one
Enabling the IP-SM-GW mode on the Next-Gen Messaging Center lets IMS subscribers message legacy subscribers immediately, with no change to the experience on either side.
Roaming SMS — IMS to legacy
Subscribers on a foreign IMS network message home-network legacy subscribers. The platform handles MAP interworking at the home network, with no change required from the roaming partner.
MVNO with its own IMS core
An MVNO running its own IMS but routing SMS via the host MNO bridges IMS messaging to the host's MAP infrastructure, with no changes to the host's systems.
SIP to MAP/SS7 translation
IMS SIP MESSAGE requests translate to MAP SM-RP PDUs for delivery via the SMSC function. VoLTE subscribers message any handset on the network with no separate client or app.
Bidirectional delivery receipts
Read and delivery notifications pass both ways across the generation boundary. Subscribers on both sides see consistent message status.
Diameter subscriber lookup
Registration status is checked via Diameter before routing. Messages reach the correct endpoint — IMS SIP client or legacy SMS — based on current registration.
Third-party SMSC compatibility
The mode connects to any SMSC supporting standard MAP or SMPP. Operators with an existing SMSC add VoLTE interoperability without replacing it.
VoLTE messaging interoperability is not optional at launch — the first IMS subscriber who sends a message needs the SIP-to-MAP bridge. Delivering it as a mode of the Next-Gen Messaging Center means operators enable a function rather than deploy and integrate another product.
The mode is available on OPEX rental, so interoperability does not have to be capitalised before VoLTE revenue arrives. It runs on the Ouroboros platform and also connects to standards-compliant third-party SMSCs — no single-vendor lock-in on the messaging stack.
Give us your IMS vendor, current SMSC, and VoLTE launch date, and we'll confirm how the IP-SM-GW mode of the Next-Gen Messaging Center fits your network.