A Menlo Park, Calif., startup has developed technology that lets people send custom text messages such as 'Hey, who's up for dinner or drinks tonight?' to multiple mobile phones simultaneously.

3jam Inc. said its short message service (SMS) technology will work on any mobile phone that supports text messaging in the United States without any special software or downloads required.

Up to 15 people can receive the same message, 3jam said. Those who receive a message can send a reply to all. One message holds up to 160 characters.

"Originally, we didn't have a limit on the amount of recipients who could receive the message, but people started using it to send spam," said Andy Jagoe, 3jam co-founder and CEO.

3jam will demonstrate the text messaging tool at DEMOfall 2006 on Tuesday in San Diego.

People likely to latch onto SMS as a communications tool are adults ages 39 and under, according Harris Interactive Inc. A online poll conducted in May among a sampling of 1,332 U.S. adults found 69 percent between the ages of 18 and 39 use text messaging, compared with 35 percent of people ages 40 to 54.

No surprise the number declines even further for those ages 55 and over, with 14 percent using text messaging and only eight percent using picture messaging, Harris said.

The NPD Group Research Director Neil Strother, who focuses on mobile devices, content and services, said if 3jam gains traction the service should become successful. "Out of all the non-voice activity there's no killer app, but this one is nice," he said. "I think they have a good shot. Now they need carriers to pick it up, or a really good marketing campaign."

No deals to announce with carriers today, but 3jam's long-term strategy will likely include buy-in from Cingular Wireless, Sprint Nextel, T-Mobile, Verizon Wireless, and others.

Fully aware voice services are a dwindling business, carriers are looking for ways to increase revenues with other services. Companies like 3jam could give carriers exactly what they seek since "strong evidence" points to upgraded data plans for people who tend to send many text messages, Jagoe said. "We've had one person who has sent 656 messages," he said.

Mobile carriers are searching for ways to add pictures in multimedia messaging. "We haven't gone that route yet, because it doesn't work for everyone," he said "Carriers are still trying to figure it out. Pictures in multimedia messaging are on their way, and that's probably where we'll go next."

To signup, send a SMS to 43526, and in the message line type "signup" and your name. You'll receive a message back indicating "You're in!" Users must add friends into an online address book, name and cellular phone number.