Shares of cloud communications platform Twilio (TWLO) - Get Report  were falling Tuesday following a report that WhatsApp, one of the company's biggest clients, was pulling back on using technology from the company and instead has turned to rival vendors. 

WhatsApp, a subsidiary of Facebook (FB) - Get Report , accounted for about 7% of Twilio's revenue last year, according to StreetInsider, which broke the news, citing sources. Twilio reported 2018 revenue of $650.1 million. Analysts expect revenue in 2019 of $1.12 billion.

During its recent third-quarter earnings report, Twilio announced that it will change its revenue recognition approach, which broke out "variable revenue" into its own category. Variable revenue describes customers that have not entered into a 12-month minimum revenue commitment contract with the company, according to StreetInsider. 

Perhaps coincidentally, WhatsApp is Twilio's largest variable customer. 

While Twilio's WhatsApp revenue isn't expected to run dry immediately, the company previously said it expects to disclose Whatsapp revenue through 2020. StreetInsider sources said that WhatsApp revenue could be out of the picture over the next several quarters. 

Earlier in the week, Twilio shares rose after RBC Capital reiterated its outperform rating and $125 price target on the stock, representing a more than 30% upside from the company's previous open price. 

Last week, the company revised its full-year earnings guidance lower due to "a simple math error," according to CEO Jeff Way. The company lowered its EPS outlook range to between 12 and 13 cents ashare from its previous expectation of between 16 and 17 cents.

Twilio shares were down 4.6% to $91.77 in trading Tuesday.

Twilio and Facebook are holdings in Jim Cramer's Action Alerts PLUS charitable trust. Want to be alerted before Jim Cramer buys or sells TWLO or FB? Learn more now.