Global System for Mobile Communications (GSM) phones raise expectations among professional-mobile-radio users to levels that system makers are only now beginning to address. Not long ago, you’d need to be a member of the emergency services or a top executive to make calls from a mobile phone. Now, anyone with $100 to spend can roam most of Europe and enjoy direct access to international communications networks. Consumer models have a lot in common with professional user needs, but there are still compelling reasons why GSM can’t deliver in the professional user market. With dedicated professional-mobile-radio backgrounds, alternative systems compete for private-mobile-radio (PMR) and public-access mobile-radio (PAMR) deployments. Now, professional users can enjoy cellular like telephony and private radio dispatcher services with the same mobile handset. Read the rest of this entry »

There are many ways to bring home a high-speed link beyond the 56-kbps limit that plain-old telephone service (POTS)-based V.90 performance allows. The methods include integrated-services digital network (ISDN), satellite links, cable modems, hybrid fiber-coax, and wireless local loops. But all these methods eventually encounter the virtually universal, metallic local loop that is the “last mile” between the phone company’s central office (CO) and the end user in the public switched-telephone network (PSTN). This loop can be a significant barrier to installing yet another type of path, or it can be a major opportunity—if you can effectively exploit the availability of this enormous, already-in-place link. Read the rest of this entry »