The information comes via an acquisition and retention study from Nokia that surveyed 20,000 mobile phone users. This is the tenth such study that Nokia has released.

Users are open to advertising from their current operators, because the brand already has their trust, says Josh Aroner, vice president of Nokia’s applications and analytics business unit. However, everyone wants an ad that is contextually relevant to them, and operators can’t afford to spoil goodwill.

“Mobile advertising is still fairly nascent—operators are moving cautiously, and they can’t be wrong,” says Aroner. “In mature markets, it’s much more a retention game than an acquisition game: You can’t do anything that will make a customer unhappy with you.”

A big part of loyalty, says Aroner, is making sure customers are taken care of—a sentiment reflected in the survey. Customer care has 60% more impact on their loyalty compared to the last study done in 2014.

In transitional markets, users were much more accepting of ads when they had rewards attached to them, but some of that sentiment may be attributable to their lack of advanced infrastructure and/or data plans.

A reward that allows you to stream more music or TV is likely to be received much more positively in such a market.