Electromagnetic interference (EMI) due to a mobile phone device has been reported to produce a detrimental effect on the function of a gamma camera system. This effect provides evidentiary support of potential bans or restrictions regarding mobile phone use within a nuclear medicine department. Methodology: A 3G Apple iPhone 6 was tested against a thyroid phantom in four operating modes, in three positions. Testing was carried out on a Siemens E-Cam gamma camera and a GE Discovery 670 SPECT/CT gamma camera. The protocols were standardized for operation on both systems with static images obtained for assessment. The static images were arithmetically assessed by means of subtraction from a baseline image, for results of potential EMI to be determined following comparison to the baseline image. Results: Initial assessment of static images acquired provided no abnormality between modes and positions. Following the application of arithmetic processes, the inferior right lobe presented with an increased ring of activity on activation of mobile signals regardless of position when tested on the Siemens E-Cam gamma camera. When compared to the GE Discovery 670 SPECT/CT gamma camera, these results did not appear to be present. This was confirmed numerically as a statistical significant difference was noted in count differences between the Siemens E-Cam and GE Discovery (P = 0.0004). Conclusion: The function of a gamma camera has the potential to be influenced by EMI produced by mobile phone devices. Further investigation is warranted employing SPECT acquisition to assess the potential for amplification of errors.