Asterisk Basic SIP Dialplan Config HD

We cover the basic configuration of an Ekiga softphone and dialplan for an Asterisk server.

[nxllpo]

is there a way to restirct one extension to be called only from certain extensions but not from all

[seeamkhan]

this is very useful and good video. thanks for this video. but i need to know how to change my ip address. Timer T1 : 500
Timer B : 32000
ToHost :
Addr->IP : (Unspecified) Port 5060
Defaddr->IP : 0.0.0.0 Port 5060
Prim.Transp. : UDP
Allowed.Trsp : UDP
Def. Username:
SIP Options : (none)
Codecs : 0x8000e (gsm|ulaw|alaw|h263)"
please help me. to change my ip address. thank you...