No. It's not just the plug that is different, but the signalling itself. The router expects to talk Ethernet via its 'RJ45' ports, but the phone line usually provides ADSL, which uses different electrical signals and carries different data formats as well.
(Not to mention that the usual kind of Ethernet requires at least two twisted pairs – four for GbE – and most phone lines I've seen only have one pair of wires...)
So, you must somehow convert the ADSL signal to an Ethernet signal, and as @sawdust already mentioned in the comments, that's called a "DSL modem".