public async Task <NumberDetailModel> GetNumberDetailAsync(string phoneNumber, int?contactId = null) { var url = $"{_httpClient.BaseAddress}NumberDetail"; var parameters = new Dictionary <string, string> { { "phoneNumber", phoneNumber } }; if (contactId != null) { parameters["contactId"] = contactId.Value.ToString(); } url = UrlHelpers.AddQueryParameters(url, parameters); var numberDetailResult = await _httpClient.GetAsync(url); if (!numberDetailResult.IsSuccessStatusCode) { await HandleErrorAsync(numberDetailResult); } return(await numberDetailResult.Content.ReadFromJsonAsync <NumberDetailModel>()); }