Introduction: Approximately 15 years ago cell phones replaced portable VHF radios as the means of communication between paramedics and base hospital physicians. Cellphones, like VHF radio, do not allow voice transmission and reception to occur simultaneously. Radio use requires a learned technique to signal the end of each speaker’s turn talking. These techniques are not used in normal cellphone conversation. Poor cellphone reception and poor technique result in breakdowns in communication. The literature about paramedic-physician telecommunication is almost nonexistent. There is an extensive literature in other industries, such as aviation, concerning problems in radio communication. This literature predicts that communication breakdowns are common and have critical consequences. We sought to determine how frequently problems attributable to cell phone technology arose in paramedic-physician communication. Methods: We conducted a retrospective analysis of all patch calls between physicians and paramedics from 4 municipal paramedic services from January 01-December 31, 2014. MP3 audio files, recorded during normal operating procedures by the Central Ambulance Communication Centre, were anonymized and transcribed. Transcripts were read multiple times by the authors and analyzed using mixed methods-qualitative thematic framework analysis and quantitative descriptive statistics. Results: 161 calls were identified. 155 tapes were usable for analysis. 127 (81.9%) patches involved termination of resuscitation orders, 28 (19.1%) were for advice or other orders. The data set consisted of 567 pages of transcripts. Communication problems were identified in 138 (89.0%) patches. Most had multiple problems. Technical problems included disconnections (13.5%), or difficulty hearing (56.8%)-indicated by phrases such as “what?”, “I can’t hear you”. Disorganized cell phone technique was common-individuals interrupted each other (34.2%), and talked simultaneously (54.8%). Signalling the end of “talk turns”-using terms such as “10-4” or “over”-was never used. Conclusion: In addition to technical problems (poor transmission, disconnections), disorganized cell phone ‘technique’ caused a high incidence of communication problems. This is concerning because critical clinical decisions (e.g. ceasing resuscitation) depend on clear communication. Understanding the limitations of cellphone technology might improve communication.