public async Task <IActionResult> MobileNumberPost(ContactPreferencesVm contactPreferencesVm)
        {
            Logger.LogInformation("Saving MobileNumber.");

            if (!ModelState.IsValid)
            {
                Logger.LogDebug("Modelstate is invalid");
                return(View("MobileNumber", contactPreferencesVm));
            }

            if (string.IsNullOrWhiteSpace(contactPreferencesVm.MobileNumber))
            {
                ModelState.AddModelError("MobileNumber", "Please enter a valid mobile number");
                return(View("MobileNumber", contactPreferencesVm));
            }

            var contactPreferencesCached = await GetFromCache <ContactPreferencesRetrievedDto>($"contact-preferences-{GetCaseflowUserId()}");

            await SaveMobileNumber(contactPreferencesVm);

            _gtmService.RaiseMobilePhoneNumberChangeEvent(contactPreferencesVm, LoggedInUserId, contactPreferencesVm.MobileNumber, contactPreferencesCached.PrimaryPhone);
            await _webActivityService.LogMobilePhoneNumberUpdateChange(contactPreferencesVm.LowellReference, LoggedInUserId, contactPreferencesVm.MobileNumber, contactPreferencesCached.PrimaryPhone);

            return(RedirectToAction("Index"));
        }