Convergence specialist Mavenir Systems Inc. has teamed up with Acme Packet Inc. (Nasdaq: APKT) in a reseller partnership designed to tackle the tricky task of delivering voice services over Long Term Evolution (LTE).

The joint proposition from the Session Initiation Protocol (SIP) proponents adds to the din of competing solutions for delivering voice over LTE. And there's a good reason why a number of different propositions are being pushed so forcefully: Many mobile operators remain undecided about how to serve up their cash cows -- voice and SMS -- to customers across their next-generation networks. (See Voice Over LTE & the 'IMS Gap' and T-Mobile, Orange Open Up on LTE.)

The two companies are targeting a technology area that is particularly problematic and divisive for mobile operators. LTE, as an all-IP network, does not support legacy, circuit-switched traffic. The only 3rd Generation Partnership Project (3GPP) -endorsed approach for delivering voice and messaging services over LTE is via IP Multimedia Subsystem (IMS), but operators view this as too immature and costly to deploy.

The new partners' solution couples Mavenir's converged voice and messaging solutions on its mOne platform with Acme's session border controllers (SBCs), creating a technology combo that allows mobile operators to deliver next-gen services, such as VoIP, using their legacy infrastructures. The idea is that operators can have next-gen apps and services without the need to deploy a complete IMS solution.

As Mavenir's Payam Maveddat, VP of product management and marketing, describes it, Mavenir's Mobile VoIP platform would enable an existing mobile switching center (MSC) to act as the equivalent of an application server in an IMS system. In addition, a combination of Mavenir's technology and Acme's SBC would, if a mobile operator has deployed 3GPP Release 4 MSCs, negate the need for additional media gateways to manage the packet voice traffic.

Different solutions, same challenge
Several competing voice-over-LTE alternatives have cropped up during the past few months, threatening fragmentation in the next-gen mobile networks market.

In one approach, dubbed circuit-switched fallback, voice services would be kicked back to the 2G or 3G networks, but this is not an elegant way to deliver voice for operators. Another is Voice over LTE via Generic Access (VoLGA), which essentially tunnels the circuit-switched traffic over the LTE IP-based network. But so far, T-Mobile International AG is the only major operator to support the Voice over LTE via Generic Access (VoLGA) Forum . (See New Specs Deepen LTE Voice Dilemma, T-Mobile: Voice Discord Threatens LTE, and New Forum Gives Voice to LTE .)

Now, Mavenir and Acme have thrown their hats into the ring with their approach, which is very similar to Nokia Networks 's own Fast Track Voice over LTE, with its MSCs that support SIP. (See NSN Goes Solo for LTE Voice.)

Mavenir is also a member of the VoLGA Forum, but Maveddat describes his company's role as more of a "monitoring member than a contributing member."

"Once we see an uptake by carriers [of VoLGA], we wll make a call about how to integrate that into our roadmap," says Maveddat, adding that it would take about six to ninth months to get such a product rolled out.

The Mavenir-Acme solution is also targeted at WiMax operators and can enable Rich Communications Suite services over 3G networks.

For mobile operators, going with a SIP-based approach now for voice services is a way to "future-proof their applications," according to Caroline Chappell, analyst-at-large at Heavy Reading.

"If you’re going to build a new application, you might as well do it in SIP," she says. "At some point in the future, you’ll be able to re-use the SIP app in the IMS environment."

In her recent report, "Telco App Servers: NGIN Revs Up for a Serious Run at SIP," she notes that IMS investment has stalled, and this has forced IMS vendors to change their tactics and sell SIP-enabled servers that support both legacy services and next-gen applications in advance of selling a whole IMS system.

And for mobile operators, "There’s even more of a cultural shock, and they’re behind the fixed-line operators," adds Chappell.

— Michelle Donegan, European Editor, Unstrung