Sprint has announced that it is testing LTE Cat-NB in its network, and will deploy the licensed-spectrum LPWAN (L-LPWAN) technology if it sees enough interest from customers. This is not the build-it-and-they-will-come approach used by its rivals, but seems wise for the number-four MNO in the market – especially as it hopes to merge with number-three T-Mobile, which is already a Cat-NB advocate. After all, why waste the energy if your merger partner has already done the hard work? For now, Sprint says it has an ongoing trial, while T-Mobile (unsurprising given its Deutsche Telekom heritage) says it has a national LTE Cat-NB network already. Earlier in the week, AT&T said it too now had a national Cat-NB network, and…