Samsung's Galaxy S9 Plus call dropping issue is seemingly much more widespread than initially thought, judging from the numerous amount of comments on the Samsung EU Community forums. Back at the end of March it was reported that a small number of people had began complaining of issues with their brand new Galaxy S9 Plus devices dropping call audio. At the time it was noted that reported problems were somewhere around the dozens and could have been limited to a specific region, but it now seems that this is a much bigger problem. On the community forum post which started back around the time of the initial report, there are now over 700 comments from various users claiming they have the same issue even after Samsung's patch update was sent out that was supposed to address and fix the issue.
Users with both Exynos and Snapdragon models as well as single SIM and dual SIM models are reporting having problems with their phones dropping call audio, so it's unlikely that this is an issue that has to do with the processor type. Some of the most recent reports from users with complaints about the bug are from today, April 27, so while it's not entirely clear just yet what the cause of the issue is, what is clear is that it doesn't appear to have been fixed. What's more is that the issue looks to be more than just dropped calls like what was described in the original report, with some users stating that calls aren't necessarily dropping out entirely but calls are getting silenced for anywhere from four to twenty seconds.
So far there are a wide range of users from various regions and other outlets reporting that this problem is happening. It's also reportedly happening on both the Galaxy S9 and Galaxy S9 Plus. Users on the EU forums are reporting the issue is popping up on devices in Serbia, Poland, South Africa, Australia, France, Germany, Israel, Jordan, Malaysia, Spain, Sweden, the UK, and various other countries. This suggests that a larger bulk of the issues are happening internationally, but it's also reported that some users in the U.S. with the phone on Sprint and T-Mobile are having the same issue as well.
At the moment, it doesn't look like there is an official fix for this issue from Samsung, though one user in the forum who goes by the name of Segar has suggested that users try to activate the Mono Audio option in the Hearing menu, which can be found under Accessibility options in the phone settings. Another user by the name of Adnaan mentions that turning this option on resulted in no change, but it's also worth noting that the same user reported making another attempt at turning this option on followed by clearing the cache, and then restarting the phone, resulting in no more dropped or silenced calls thus far. That being said this may be a short-term workaround for users experiencing the issue. Multiple users have also reported that Samsung has been working with them to offer exchanges to a new handset as part of a replacement, though it's not clear if this is only happening for those who bought the device directly from Samsung or not, and many of those reporting having gotten replacements are also claiming to have had the issue with the replacements as well leading to multiple exchanges. So far the forum, which you can find linked below, is littered with complaints and reports from a very large number of users, yet there doesn't seem to be any responses from Samsung in the thread at this time. Samsung is likely trying to find a permanent fix that isn't a simple phone exchange, especially if this doesn't appear to be working. For now, any users experiencing this issue may want to try the workaround that was explained just above as it might stop dropped calls or silenced calls even if only for a shorter period of time.