! Execute a shell command
abort halt Cancel a running halt
add extension Add new extension into context
add ignorepat Add new ignore pattern
add indication Add the given indication to the country
answer Answer an incoming console call
autoanswer Sets/displays autoanswer
database del Removes database key/value
database deltree Removes database keytree/values
database get Gets database value
database put Adds/updates database value
database show Shows database contents
debug channel Enable debugging on a channel
dial Dial an extension on the console
dont include Remove a specified include from context
dump agihtml Dumps a list of agi command in html format
extensions reload Reload extensions and *only* extensions
hangup Hangup a call on the console
help Display help list, or specific help on a command
iax1 debug Enable IAX debugging
iax1 no debug Disable IAX debugging
iax1 set jitter Sets IAX jitter buffer
iax1 show cache Display IAX cached dialplan
iax1 show channels Show active IAX channels
iax1 show peers Show defined IAX peers
iax1 show registry Show IAX registration status
iax1 show stats Display IAX statistics
iax1 show users Show defined IAX users
iax2 debug Enable IAX debugging
iax2 no debug Disable IAX debugging
iax2 set jitter Sets IAX jitter buffer
iax2 show cache Display IAX cached dialplan
iax2 show channels Show active IAX channels
iax2 show peers Show defined IAX peers
iax2 show registry Show IAX registration status
iax2 show stats Display IAX statistics
iax2 show users Show defined IAX users
iax2 trunk debug Request IAX trunk debug
include context Include context in other context
init keys Initialize RSA key passcodes
load Load a dynamic module by name
logger reload Reopens the log files
logger rotate Rotates and reopens the log files
mgcp audit endpoint Audit specified MGCP endpoint
mgcp debug Enable MGCP debugging
mgcp no debug Disable MGCP debugging
mgcp show endpoints Show defined MGCP endpoints
no debug channel Disable debugging on a channel
pri debug span Enables PRI debugging on a span
pri intense debug sp Enables REALLY INTENSE PRI debugging
pri no debug span Disables PRI debugging on a span
reload Reload configuration
remove extension Remove a specified extension
remove ignorepat Remove ignore pattern from context
remove indication Remove the given indication from the country
restart gracefully Restart Asterisk gracefully
restart now Restart Asterisk immediately
restart when conveni Restart Asterisk at empty call volume
send text Send text to the remote device
set verbose Set level of verboseness
show agents Show status of agents
show agi Show AGI commands or specific help
show applications Shows registered applications
show application Describe a specific application
show audio codecs Shows audio codecs
show channels Display information on channels
show channel Display information on a specific channel
show codecs Shows codecs
show codec Shows a specific codec
show conferences Show status of conferences
show dialplan Show dialplan
show image codecs Shows image codecs
show image formats Displays image formats
show indications Show a list of all country/indications
show keys Displays RSA key information
show locals Show status of local channels
show manager command Show manager commands
show manager connect Show connected manager users
show modules List modules and info
show parkedcalls Lists parked calls
show queue Show status of a specified queue
show queues Show status of queues
show switches Show alternative switches
show translation Display translation matrix
show uptime Show uptime information
show version Display version info
show video codecs Shows video codecs
show voicemail users List defined voicemail boxes
show voicemail zones List zone message formats
sip debug Enable SIP debugging
sip no debug Disable SIP debugging
sip reload Reload SIP configuration
sip show channels Show active SIP channels
sip show channel Show detailed SIP channel info
sip show inuse List all inuse/limit
sip show peers Show defined SIP peers
sip show registry Show SIP registration status
sip show users Show defined SIP users
skinny debug Enable Skinny debugging
skinny no debug Disable Skinny debugging
skinny show lines Show defined Skinny lines per device
soft hangup Request a hangup on a given channel
stop gracefully Gracefully shut down Asterisk
stop now Shut down Asterisk immediately
stop when convenient Shut down Asterisk at empty call volume
transfer Transfer a call to a different extension
unload Unload a dynamic module by name
zap destroy channel Destroy a channel
zap show channels Show active zapata channels
zap show channel Show information on a channel

Follows is a session that I did when I called Dave...
(Note: most of these have lots of extra embedded spaces in a feeble attempt to make columns)

sip show channels
Peer User/ANR Call ID Seq (Tx/Rx) Lag Jitter Format
66.116.94.76 david 7aa7f67c411 00102/00000 00000ms 0000ms ULAW
66.116.94.66 2023 0E5AFC04-CF 00101/17185 00000ms 0000ms ULAW
2 active SIP channel(s)
 

sip show channel
0E5AFC04-CF67-437B-845B-E10B0D88BA05@66.116.94.66
7aa7f67c4112ba8b3a56484709bbe128@66.116.95.200
 

sip show channel 0e
Call-ID: 0E5AFC04-CF67-437B-845B-E10B0D88BA05@66.116.94.66
Our Codec Capability: 12
Non-Codec Capability: 0
Joint Codec Capability: 12
Theoretical Address: 66.116.94.66:5060
Received Address: 66.116.94.66:5060
NAT Support: No
Our Tag: 1770978502
Their Tag: 1390868425
Need Destroy: 0
Last Message: Rx: ACK
DTMF Mode: inband

No such SIP Call ID starting with '0e'
 

sip show
channel channels inuse peers registry users
 

sip show inuse
Username incoming Limit outgoing Limit
2125 0 N/A 0 N/A
2123 0 N/A 0 N/A
2122 0 N/A 0 N/A
2025 0 N/A 0 N/A
2023 1 N/A 0 N/A
2022 0 N/A 0 N/A
fwd 0 N/A 0 N/A
 

sip show peers
Name/username Host Mask Port Status
2125/rosemary (Unspecified) (D) 255.255.255.255 0 UNKNOWN
2123/david (Unspecified) (D) 255.255.255.255 0 UNKNOWN
2122/david (Unspecified) (D) 255.255.255.255 0 UNKNOWN
2025/rosemary 66.116.94.77 (D) 255.255.255.255 5060 OK (9 ms)
2023/chris 66.116.94.66 (D) 255.255.255.255 5060 OK (7 ms)
2022/david 66.116.94.76 (D) 255.255.255.255 5060 OK (20 ms)
fwd/275809 192.246.69.223 255.255.255.255 5060 Unmonitored
 

sip show registry
Host Username Refresh State
192.246.69.223:5060 275809 120 Registered
 

sip show users
Username Secret Authen Def.Context A/C
2125 default No
2123 surfcity No
2122 surfcity No
2025 surfcity No
2023 surfcity No
2022 surfcity No
fwd rosemary md5,plaintext aa No