Couldn't tell you for sure without some form of datasheet (which you probably won't find from them). But in all likelihood it should be fine - 1.3A isn't actually a massive amount, especially over only a couple of metres. Anything larger than 28AWG should be able to handle that current level - and most of the RJ11 cables you'll find will probably be 26AWG or even 24AWG, so would be fine.