NICE, France -- TM Forum Live! 2015 -- Telecom Italia has flagged concern that virtualized silos could emerge, negating some of the benefits of virtualization, unless there is swifter progress on NFV standardization and interoperability.

Speaking this week at the TM Forum 's annual conference in Nice, Mario Bonnet, who heads up network virtualization for the Italian operator, said Telecom Italia (TIM) was facing a number of challenges on the orchestration front, with orchestrators "popping up like mushrooms on a rainy day."

"Is there a mature multivendor orchestrator environment?" he asked conference attendees. "We find it difficult to have orchestration between products from different vendors … and there is a risk we end up with virtualized silos that are not effective anymore."

Interoperability has emerged as a critical need as operators look to work with a variety of NFV vendors and avoid becoming overly dependent on a single provider.

Orange (NYSE: FTE) and Telekom Austria Group are two high-profile European operators that are already taking a multi-vendor approach to the rollout of NFV and SDN technology, and other service providers are clearly keen on charting a similar path. (See Orange Unveils NFV-Based Offering for SMBs and Telekom Austria Builds Multi-Vendor NFV 4G Core .

Presenting at the same TM Forum session as Bonnet, SK Telecom (Nasdaq: SKM)'s Jason Park, who manages packet core development for the Korean operator, revealed that he is conducting interoperability tests with three vendors during an NFV implementation.

Colt Technology Services Group Ltd , regarded as something of a pioneer when it comes to NFV and SDN, is another service provider eager to move to a fully standardized, multi-vendor solution in the future.

"We have a solution that works very well but we can't evolve it too much," said Mirko Voltolini, Colt's vice president of technology and architecture, in response to questions about the company's virtualization strategy. "We've done a PoC [proof of concept] over the last nine months and are ready to go into production … but it's hard for vendors to come up with the right business model from a pricing perspective."

Voltolini's remarks clearly imply that interoperability is not the only barrier to the use of several vendors during an NFV rollout.

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Colt has been working with Accedian , Cyan Inc. and Juniper Networks Inc. (NYSE: JNPR) on the deployment of a virtual CPE -- claiming this has led to cost reductions and greater service agility --- but the carrier appears interested in bringing more players on board as it virtualizes other parts of its business. (See Colt Bigs Up the Benefits of Virtual CPE .)

"During the recent PoC we validated a number of VNFs [virtualized network functions]," says Voltolini. "The hope is that we'll be able to pick and choose from different suppliers."

Earlier this week, BT Group plc (NYSE: BT; London: BTA) also emphasized the importance of interoperability during a presentation on the UK incumbent's NFV and SDN strategy. (See BT Predicts SDN/NFV Vendor 'Shake-Out'.)

Chris Bilton, BT's director of research and technology, went on to say that some of the smaller and less well-known suppliers targeting the NFV opportunity may be "stealing a march" on the established vendors.

Similar to Colt, Telecom Italia says it is running PoCs with several orchestration vendors to assess interoperability, but Bonnet urged Sami Pohjonen, the head of OSS for Nokia Networks , to "provide answers to our challenges."

Following Bonnet on to the presenters' stage, Pohjonen insisted that Nokia is working "openly and in a modular way" to ensure that customers could avoid "vendor lock-in."

Pohjonen said the Finnish player is working alongside various NFV partners and has teamed up with Comptel Corp. (Nasdaq, Helsinki: CTL1V) on service orchestration capabilities for its Telco Cloud initiative.

— Iain Morris, , News Editor, Light Reading