怎么理解Wikipedia上关于IMS的这段话？

pairskating

怎么理解Wikipedia上关于IMS的这段话 （我用黑体字标出的话）？

下面的文字均摘自Wikipedia：
http://en.wikipedia.org/wiki/IP_Multimedia_Subsystem#cite_note-1

The IP Multimedia Subsystem (IMS) is an architectural framework for delivering Internet Protocol (IP) multimedia  services. It was originally designed by the wireless standards body 3rd Generation Partnership Project (3GPP)...

To ease the integration with the Internet, IMS uses IETF protocols wherever possible, e.g. Session Initiation Protocol (SIP). According to the 3GPP, IMS is not intended to standardize applications but rather to aid the access of multimedia and voice applications from wireless and wireline terminals, i.e. create a form of fixed-mobile convergence (FMC)...

Alternative and overlapping technologies for access and provisioning of services across wired and wireless networks include combinations of Generic Access Network, soft switches and "naked" SIP. It is easier to sell services than to sell the virtues of "integrated services", but additionally the task to sell an IMS based on a single service is also difficult as there are often (cheaper) alternatives to creating and deploying that particular service.
Since it is becoming increasingly easier to access content and contacts using mechanisms outside the control of traditional wireless/fixed operators, the interest of IMS is being challenged.

虽然可以明白中文字面意思，但这段话背后的含义我不是很理解。
希望牛人帮忙解读。谢谢！ :)

[ 本帖最后由 pairskating 于 2010-3-24 21:39 编辑 ]