IDC’s latest quarterly mobile phone tracker contains a mix of good news and bad for Apple. It starts by noting that 2015 was a fantastic year for the company in terms of both sales numbers and average selling price.

2015 was a tremendous year for Apple and the iPhone as shipments hit a new record of 231.5 million for growth of 20.2% over 2014, which was nearly double that of the overall smartphone market. More importantly, Apple was able to grow its ASP from $663 in 2014 to $713 in 2015.

Things get tougher this year, it suggests, forecasting flat sales for the year (or a drop of 0.1% if we wanted to pretend that forecasts could ever be that accurate) …

2016 will be difficult, it says, due to slowing growth in Apple’s core markets of the USA, Europe and China. The greatest growth at present is in markets currently buying cheaper brands, like India and Africa.

The mature market slowdown has some grave consequences for Apple, as well as the high-end Android space, as these were the markets that absorbed the majority of the premium handsets that shipped over the past five years.

However, IDC believes that Apple’s move into trade-in programs for both older iPhones and Android handsets will help with sales, the firm forecasting that ‘peak iPhone‘ will be over by next year.

However, growth should return in 2017 and beyond as its trade-in programs will expand into markets outside of North America and help drive churn.

Apple launched its first trade-in program back in 2013, but with limited impact. You’d almost always get a better deal selling on eBay or similar and then paying cash for your new iPhone. But Apple really upped its game last year, launching first a trade-in scheme for competitor phones, then the iPhone Upgrade Program, a trade-in scheme for broken phones and a ‘trade-up with instalments‘ plan.

IDC does, though, believe future iPhone growth will be relatively modest, with a projected compound annual growth rate of 3% between 2016 and 2020.

The company last week reported that Apple Watch sales hit 4.1M in the final quarter of 2015, making Apple number two in wearables behind Fitbit.