If you are using Sermo Mobile to reach your patients, but find that calls are not connecting, the issue may be related to either your mobile carrier or local country-level telecommunications regulations.
We understand how disruptive this can be when you need to communicate with patients. Below, we explain why this may happen and what steps you can take to continue using Sermo Mobile successfully.
The Issue: Carrier and Country Restrictions on Call Spoofing
Sermo Mobile uses call-masking technology to protect your privacy by displaying a different number instead of your personal phone number. This process is sometimes referred to as caller ID spoofing.
While your number may be fully validated within Sermo, some mobile carriers and national telecom regulators restrict or block masked calls, regardless of validation. In these cases, calls may fail to connect, be blocked instantly, or never ring.
These restrictions are imposed outside of Sermo Mobile and cannot be overridden within the app.
Country-Level Restrictions
In some countries, regulations require telecom providers to block calls that use masked or altered caller IDs, therefore preventing Sermo Mobile calls from connecting.
Identified countries with restrictions:
Germany
Italy
India
Additional countries may enforce similar regulations, and enforcement can vary by provider.
Carrier-Level Restrictions
At this time, we have identified two carriers with known restrictions:
Movistar
Movistar is a major telecommunications provider operating primarily in Spain and parts of Latin America, including Mexico, Colombia, Argentina, Chile, and Peru.
Telstra (France)
While there are no known legal requirements preventing call spoofing in France, Telstra users may experience restrictions.
If you're subscribed to one of these, you may experience calls that fail immediately or never connect when using Sermo Mobile.
How to Resolve
We recognize that changing numbers or carriers can be inconvenient. However, to successfully use Sermo Mobile, you must use a phone number that is not affected by carrier or country-level restrictions.
Recommended Steps:
Try a secondary line: If you have a work phone or a dual-SIM device with a different carrier, validate and use that number instead.
Use a different device: Place calls from a device registered with another mobile provider.
Avoid restricted regions or carriers: If possible, use a number from a country or carrier that does not block masked caller IDs.
Note: Please be advised that you may encounter difficulties when contacting patients whose telecom providers are not listed. In some cases, carriers may unintentionally block your calls as part of their efforts to protect customers from spam and fraudulent call activities.
Sermo continuously monitors carrier compatibility and regulatory changes to provide the best possible experience. If you encounter issues with another carrier or country, or need help updating your phone number, please contact our support team. We’re here to help you stay connected.