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Configuring Cisco 7940g phone for stanalone SIP ?

Level 1
Level 1

I have a Cisco 7940g IP telephone.

I do not have a PBX. This is simply an IP phone plugged into a my LAN.

I just signed up Digium cloud SIP service.

Is there a way to make this work?

P.S.   I tried entering the credentials that Digium sent me into the "5.  SIP Configuration" menu under "SETTINGS" on the phone, but I still have an 'X' over my line on the home screen.   :-(

3 Replies 3

Leo Laohoo
Hall of Fame
Hall of Fame

Digium is a very-well known company because of a VoIP product called Asterisk.

Will the phone work, of course.  You have a choice of running SIP or Cisco-proprietary SCCP.  

We'll need to do a top-to-bottom troubleshooting and configuration.  Firstly, what protocol are you planning to use (SIP or SCCP) and what configuration settings does Digium require you to do from your side?

I want to run SIP.  I do not have any PBX or other Cisco phone hardware outside of this 7940g phone sitting on my desk.

I have factory-reset the phone, and entered the credentials Digium gave me.

Settings > 4. SIP Configuration > 1. Line 1 Settings:

1. Name = (my assigned Digium phone number)

2. Shortname = (my name)

3. Authentication Name = 56605ed547a8437d872f6b516df6a4bc

4. Authentication Password = (another random string of characters just like the previous field)

5. Display Name = UNPROVISIONED

6. Proxy Address =

7. Proxy Port = 5060

I have confirmed with our sysadmin that the network's router is set to (1) disable "SIP helper", and (2) allow communication on specific UDP port ranges, both per Digium's knowledgebase.

Those configuration are not enough.  

Ask Digium if NAT & ALG are supported. 

What transport protocol does Digium support:  TCP or UDP

What codec is allowed?

79X5 family of phones behave differently.  It's not like the 79X0 where the configurations are simple.  You'll need to upload the complete set of configurations to the phone using DHCP Option 150 and a TFTP server.