Voice service is something a great deal of mobile subscribers take for granted. It is no longer a differentiator for MNO’s and MVNO’s in their service offerings. In fact, many mobile plans include unlimited voice.

Data, email access, texting, and mobile apps like WhatsApp, are the services most subscribers look for when selecting their plan. And I’d venture to say that for a growing number of subscribers, voice is becoming a “nice to have”, but not necessary service.

Voice is a given, a commodity, a service that is always there and available. A good thing about living in Europe is that European mobile operators make basic voice/sms service quite convenient to use even when using it outside of Europe—and depending on where you roam, it can be relatively inexpensive compared to mobile data. On the other hand, data roaming packages for regions outside of Europe don’t come cheap, and Wi-Fi is not always available.

So, what if that basic service fails? And can it happen? I never really wondered nor considered the possibility, which really says something about the high availability of GSM circuit switched networks. If anything, when roaming, my worry is data and email access. But voice? Never!

I thought this way until a recent trip to Israel where I was going to use only voice and carefully use mobile data roaming to avoid astronomical charges. Upon landing, I got automatically connected to one of the Israeli MNO’s randomly selected by my home provider. 3G data (not surprised I did not get 4G) worked flawlessly. However, when I attempted to make a voice call, which was my “go-to” service, it failed!

How was that possible? I had access to data, and I was getting emails. But no voice and sms service? Voice was the only option I had to reach the people I was going to meet. I could not reach them on WhatsApp or Viber since they did not have an account. So, my only resort was calling them or texting them. Ironically, I couldn’t even reach my provider’s customer service, as it is reachable by voice or text only!

Mobile operators will steer roamers to certain visited carriers, and it appeared that the one I ended up camping on blocked my voice calls.  Had it been data, I would not have cared that much since sooner or later I would have had access to Wi-Fi and snap! Problem solved.

But voice access, unlike data access has limited alternatives, at least for now. My domestic carrier does not yet support VoLTE, and I was on 3G, so I could not expect VoLTE roaming to save me. The signaling that goes on between your mobile phone, the visited network, and the network of your domestic provider gets pretty complex. This is especially the case if you’re trying to connect to a 3G home network with a 4G device.

There can also be intermediary networks involved called GRX (GPRS Roaming Exchange) or IPX  (IP Exchange operators) who may also be playing a role in steering your device to a particular visited operator on behalf of the home network.  Mobile providers and IPX operators are starting to deploy Diameter Signaling Controllers (DSCs) that help enable roaming interworking for both 4G and 3G subscriber devices and help them better manage the user experience when it comes to roaming. But for now, it seemed when it came to voice, you have it or you don’t. And when I didn’t, I found out I couldn’t go without it.

I eventually found the solution: I disabled the automatic network selection on my smartphone, and hoped my provider had a roaming agreement with more than one Israeli operator. To my relief, it did. My voice service was finally working, and I got my voice back!

Have you ever thought your voice service could fail? Is voice still an important service you value? Tell us your thoughts and share your experience by twitting us @Dialogic