Just two months after handing over the reins of its network to Ericsson, 3 U.K. announced today it has awarded a major network core upgrade from Ericsson’s arch competitor Nokia.

Nokia will deploy its MSC Servers, media gateways and Flexi intelligent service node, all built under 3GPP Release 4 specifications. R4 is a next-generation architecture, which separates the signaling from the call in the network, allowing carriers to centralize their call control but keep their switching on the network edges where most traffic is concentrated. Nokia also will be upgrading its own legacy equipment in the 3 core, which it installed when 3 first built its UMTS-only network in 2001.

The deal is not only a significant infrastructure deal for Nokia, but also a slightly surprising one. Since Nokia was the exclusive core equipment provider for 3’s U.K. network, it was the obvious candidate for the upgrade, but in December the carrier handed over the management of its entire network to Ericsson’s Global Services division, putting the Swedish vendor in charge of all network planning, maintenance and day-to-day management for the next seven years. While it seemed likely that the deal would be a direct supply-line into 3 for Ericsson network gear, the fact Nokia was tapped for a such a massive core overhaul lends credence to Ericsson’s claim that it would keep its infrastructure and professional services businesses completely separate.

When Ericsson landed the multi-billion dollar services deal, Ericsson Global Services general manager Hans Vestberg said Ericsson had no intention of pushing its own equipment on 3 or any of its other managed services clients. “We do not make the technology choices,” Vestberg said in an earlier interview with Telephony.

Nokia named no financial terms of the deal