The short message and multimedia message services (SMS and MMS) of China's three telecom carriers saw declines of over 20 percent in 2012, according to the Data Center of China Internet (DCCI), but an expert told the Global Times Thursday that the decline may be overstated.

The total number of SMS messages sent via the three carriers dropped 20 percent year-on-year in 2012 and the number of MMS messages plunged 25 percent over the same period, according to Hu Yanping, director of DCCI, in late December.

Experts noted that the increasing popularity of WeChat, the mobile chat app under Internet firm Tencent, and of Sina's Twitter-like platform Weibo, is a major reason behind the drop in SMS activity.

"Mobile phone services are no longer consumers' first choice as smartphones have provided various means of instant communication," Sun Peilin, a senior IT industry researcher at consultancy Analysys International, told the Global Times Thursday.

New Year's Day and the Spring Festival used to be a high time for Chinese people to send SMS greetings, but this year many of them have turned to new methods such as WeChat and Weibo.

"I sent my New Year's greetings to my friends via WeChat this year. I only text my parents or other older people who are not used to using smartphones," Li Shanshan, a Beijing-based white-collar worker, told the Global Times.

WeChat has seen its total users surpass 200 million in less than two years. The number is likely to top 300 million in January, Ma Huateng, CEO of Tencent, said in a forum in Guangdong in December.

China Mobile, the country's largest mobile operator, now has over 700 million users, and both China Unicom and China Telecom have over 200 million.

Media reports have said that the Ministry of Industry and Information Technology (MIIT) is mulling detailed rules to further open the telecom sector to private investors, and licensed firms would then be eligible to provide telecommunications services via the Internet.

Experts said Tencent is likely to be among the first Internet firms to enter the sector.

Xiang Ligang, president of industry information portal cctime.com, said that although multimedia chat software such as WeChat has diminished SMS traffic, it is still too early to say that such software threatens the three carriers, as it could also bring them mobile Internet traffic.

Xiang also raised doubts about the data from DCCI, saying it is not very likely that the three companies would see such large declines in 2012, considering official MIIT data from the first 11 months. That data showed that although the three operators have seen SMS growth decline steadily in the January-November period, but the rate has still remained well above 2 percent each month.