Telnet is used to access a router remotely but how many simultaneous Telnet sessions are supported on a Cisco router by default?

I think its5 sessions : line vty04

by default it supports 5 telnet sessions: line vty 04

Actually, default on all cisco boxes is 5. line vty 04.  You actually have to light up the other 10 by adding the line vty 515.  Example below...  Hope this helps.  I'd put the Todd Laramie book down.  WAY to many discrepancies in the 2 books, I've had this debate with many...

(default)

line vty 04 access-class 147 in exec-timeout 300 password 7 xxxxx

(add)

conf t

line vty 515 access-class 147 in password 7 xxxxxx

by default 5 sessions(vty 04)

By default Cisco router support virtual teminal interface 0-4 (5 total) which are used for telnet sessions

5 session can be used by cisco routers.

5 session

 should configure router by CLI

By default you can't talent the router so you have to configure your device to accept telnet and you can specify the needed VTY lines which will indicate to you the simultaneous telnet sessions and the maximum telnet session is varying from one device to another based on the hardware and software capabilities.

Default on all cisco router is 5 telnet sessions.line vty 04.We can also add 10 more by line vty 515.

Cisco Press book states the maximum concurrent telnet sessions is16.  I believe it could be varie with the platform and/or ios set.