It’s good to be king, but ensuring your kingdom continues to expand is always a top priority. According to a recent report from ABI Research, the world’s top-10 wireless carriers — which include Verizon Wireless (No.2) and AT&T (No.4) — took in a combined $202 billion in gross profit last year. That 2012 total is up 4.2% compared to the prior year, but high plan prices and growing subscriber bases aren’t drumming up the growth rates they used to. “As the underlying lift from accumulating subscribers has matured, carriers are starting to cast around for additional revenue streams that don’t just boost revenues but also profitability,” said ABI analyst Jake Saunders. “There is still tremendous income to be generated from mobile services; the Top 10 Mobile Carriers alone generated US$202 billion in gross profit, up 4.2 % year-on-year in 2012.” According to the research firm, IP-based value-added services are now a big focus for top carriers as they look elsewhere for growth opportunities.