Question regarding Asterisk and GSM Mobile Phones


I’m interested of building an Asterisk PBX for my office, but have a question regarding how to integrate it with GSM mobile phones.

Basically, what I need to be able to do is to transfer all calls coming to my office phone (extension) to my GSM mobile phone, when I’m outside the office. I would like to also have the telephone number of the caller (Caller ID) to show up on my mobile phone when it rings, instead of it showing my office number.

So what hardware and software requirements do I need to make this possible?

Thanks for your help.

A PSTN gateway. Either analog or ISDN.

Then you declare the cellphone as a simple extension of asterisk.
You can do this static or dynamically.


exten=> 5554433,1,Dial(SIP/John&Zap/g1/cellphonenumber)

That would ring your desktop phone (SIP) and your cellphone via a ZAP trunk (ISDN card) simultan.

exten=> 5554433,1,Dial(SIP/John,30) ;Ring Johns desk 30s
exten => 5554433,2,Goto(john-${DIALSTATUS},1)

;John didnt answer, lets forward to cellphone
(You might need an “ANSWER LINE” first at this point)
exten => john-NOANSWER,1,Playback(forwarding-to-slacker-johns-cell)
exten => john-NOANSWER,2,Dial/ZAP/g1/cellphonennumber,45)
exten => john-NOANSWER,3,hangup

;Cellphone wasnt answered too: Lets shove lazy John a voicemail now
exten => john-NOANSWER,102,voicemail(b5554433)
exten => john-NOANSWER,103,hangup

Example made out of mind, might be buggy.