form.html

        <form class="register-form" method="POST" autocomplete="on">
          <div class="input-group mb-3">
            <div class="input-group-append">
              <div class="input-group-text">
                <span class="fas fa-mobile"></span>
              </div>
            </div>
      
                  <input type="number" class="form-control" name="phone" value="" pattern="09(0[1-2]|[0-9][0-9]|3[0-9]|2[0-1])-?[0-9]{3}-?[0-9]{4}" maxlength="10" size="10" placeholder="موبایل ،مثلا: 09981152407" required>
      
          </div>
          <div class="row">
            <div class="col-8">
              <div class="icheck-primary">
                <input type="checkbox" id="agreeTerms" name="terms" value="agree" checked>
                <label for="agreeTerms">
                    با <a href="#"> شرایط و مقررات </a> موافق هستم
                </label>
              </div>
            </div>
            <!-- /.col -->
            <div class="col-4">
              <input type="submit" class="btn btn-primary btn-block" value="ثبت">
            </div>
            <!-- /.col -->
          </div>
        </form>