Research In Motion customers such as GoDaddy and asset manager Thames River Capital UK are preparing for the worst: the loss of the BlackBerry service their employees depend on to communicate.

RIM’s stock has slumped more than 70 percent in the past year, and it tumbled 19 percent June 29 after the company posted a quarterly loss and delayed the BlackBerry 10 operating system, increasing pressure on RIM to find a buyer or sell assets. While RIM has built infrastructure to ensure continued service, some customers are devising backup plans.

“In the past three months there’s been a lot of concern that the BlackBerry platform won’t be around in the future,” said Maribel Lopez, founder of Lopez Research, a wireless-industry consultant based in San Francisco.

Corporate customers, the backbone of RIM’s business, are fortifying contingency plans so they won’t be affected by a possible breakup of the BlackBerry maker or other setbacks. With millions of employees connecting to the office through mobile email, companies have been eager to establish a fallback or replacement plan, said Avi Greengart, a technology research director at Current Analysis.

Thames River Capital supplies about 140 of its 170 employees with smartphones, most of them BlackBerrys, said Robert Cockerill, head of infrastructure at the London-based money manager. With the delay of BlackBerry 10 and a service contract with RIM expiring this year, Cockerill said he expects much of his staff to switch to Apple’s iPhone or devices based on Google’s Android platform.

Cockerill has brought in MobileIron, a Mountain View, Calif.-based developer of software that helps companies manage and protect data on mobile devices and tablets. MobileIron provides security for Thames River Capital including encryption and password protection for non-BlackBerry devices such as iPads, he said.

Thames River Capital is preparing for scenarios where BlackBerry service may be shut down, disrupted, or if a competitor such as Microsoft acquires RIM and converts the operating system to its Exchange email service, he said.

“There is a risk of RIM getting bought,” Cockerill said. “But if you have the right support, you can be agnostic and it won’t really matter.”

MobileIron CEO Bob Tinker said his customer list includes 100 Fortune 500 companies; about a quarter of them are in financial services.

“Large enterprises don’t want to be locked in with a single vendor anymore,” Tinker said in an interview. Customers want to embrace all the innovation in mobile, and RIM’s delay of BlackBerry 10 doesn’t help that, he said.

“CIOs are now asking us: ‘What do we do if RIM gets acquired or if they restructure,’ ” Tinker said.

Norton Rose LLP, a law firm with 6,000 BlackBerry-equipped employees, is using MobileIron’s software to support iPhones and iPads, which were given to some staff members as secondary devices, said Vlad Botic, group enterprise architect at the London-based firm.

Botic, who said Norton Rose would like to continue using BlackBerrys, began exploring alternatives last year after the three-day BlackBerry outage that caused users around the world to lose data services amid a network failure.

“RIM isn’t in a good position right now,” Botic said. “The problem with BlackBerry, which was highlighted when the service went down, was that the only way to solve it is with an entirely new device.”