I used his phone to call the helpline.

我用他的电话拨打了服务热线

If you have a query about your insurance policy, contact our helpline.

若对保险单有疑问，请拨打我们的咨询热线。

There's no helpline.

这里没有求助服务热线。

Then I used his phone to call the helpline.

然后我用他的电话拨打了服务热线。