T-Mobile US became the latest operator to sign up for the Ubuntu Carrier Advisory Group, a move which will see it “join discussions to influence the development of Ubuntu for smartphones”.

The group was open to new members until the end of July 2013, meaning that the US number four operator is likely to be the last partner announced. The body has previously succeeded in securing some significant backers, including China Unicom and Verizon Wireless.

The alliance offers supporters “a period of exclusivity to ship Ubuntu in their markets”, but now has two members from the US.

Other named members of the Carrier Advisory Group are Deutsche Telekom, EE, KT, Smartfren, Telecom Italia, LG U+, Portugal Telecom, SK Telecom and MTN.

While the Ubuntu platform now has a solid roster of supporting operator partners, it is somewhat lacking in terms of support from device makers.

Canonical, the company behind the operating system, last month kicked off a $32 million crowdfunding scheme intended to support the development of the first smartphone, called Ubuntu Edge, although at the moment it is tracking someway behind its target.