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New Member

7960 SIP in standalone mode

Hello:

I have a 7960 running SIP 3-4-3-00 image. I'd like to have the phone

operate in "unregistered" mode. This means not registered with our

proxy. If I comment out the proxy addres in the config file the phone

boots to an unprovisioned state. If I leave the proxy address in the

config but specify not to register then outbound calls fail with a

reorder tone.

A packet trace shows the phone trying to resolve the address against

the SRV record for the proxy server even though I said not to register.

In the end I get a 604 status - does not exist anywhere and the reorder

tone plays in the handset.

In this specific example the "userid" portion of the SIP destination

address was indeed a local 11 digit telephone number while the

"host" portion was a numeric IP address. The process fails in other

scenerios also.

So. If I'd like to operate in unregistered mode, yet get the phone config

from our tftp server and be able to do URL dialing with addresses that

contain either alpha-numeric userids or numeric strings that look like

DNs how can this be done?

Thank you,

Steve Blair

4 REPLIES
Cisco Employee

Re: 7960 SIP in standalone mode

Here's a solution for numeric dialing and alpha dialing.

An example with 2 phones calling each other. This can be adapted to point to a gateway instead of another phone:

SIP7960_1

--------------------------------

mac address = 003094C283B9

IP address = 10.10.1.1

SIP address for Line1 = 45731

SIP address for Line2 = user1

SIP7960_2

--------------------------------

mac address = 003094C283A7

IP address = 10.10.1.2

SIP address for Line1 = 45732

SIP address for Line2 = user2

In the SIP.cnf file for both phones make sure to set the proxy_register field to 0 and the following for the line appearance config (everything else should be standard SIP phone config):

[for SIP7960_1]

# Phone Number

line1_name: 45731

line1_shortname: 45731

line1_authname: ""

line1_password: ""

proxy1_address: 10.10.1.2

proxy1_port: 5060

line2_name: user1

line2_shortname: user1

line2_authname: ""

line2_password: ""

proxy2_address: 10.10.1.2

proxy2_port: 5060

[for SIP7960_2]

# Phone Number

line1_name: 45732

line1_shortname: 45732

line1_authname: ""

line1_password: ""

proxy1_address: 10.10.1.1

proxy1_port: 5060

line2_name: user2

line2_shortname: user2

line2_authname: ""

line2_password: ""

proxy2_address: 10.10.1.1

proxy2_port: 5060

-----------

Basically, we configure the line appearances to point directly to the IP address of the other phone. In this case, we configured 2 line appearances to point to the same destination IP, one for numeric dialing and one for alpha dialing. You could configure each line appearance to point to a different endpoint, if that's what you want.

The same premise applies when configuring an IP phone to point to a gateway.

With IP phone to GW config, the GW would need a dial-peer for each phone. You can't configure a bunch of VoIP dial-peers and point the phone to the GW and make phone to phone calls as IOS does not support tandeming of VoIP calls, but you could place calls to/from the PSTN.

Expanding on the above example, on SIP7960_1 I could configure line3 to point to a SIP gateway and make calls to the PSTN using that line appearance, but to call to SIP7960_2, I would need to use either line1 or line2.

HTH,

Clay

New Member

Re: 7960 SIP in standalone mode

Thanks Clay. I need to digest what you suggest to see if it addresses

the issue I am experiencing. I noticed you said "... to point to the same

destination IP...". This suggests that FQDNs in this field either won't

work or will be treated as SRV records instead of A records. Has this been

your experience or were numeric IP addresses simply easier to work

with?

Thanks,Steve

Cisco Employee

Re: 7960 SIP in standalone mode

Hi Steve -

With the phone configured for FQDNs, I took a look at it in my lab and here's the tcpdump from the DNS server without SRV records in the DNS database:

09:11:53.882723 14.50.6.102.52214 > ms-sipserver2.cisco.com.domain: [no cksum] 54+ SRV ? _sip._udp.ms-sipserver1.cisco.com. [|domain] [tos 0x10] (ttl 63, id 8396, len 79)

09:11:53.892723 ms-sipserver2.cisco.com.domain > 14.50.6.102.52214: 54 NXDomain q: SRV ? _sip._udp.ms-sipserver1.cisco.com. 0/1/0 ns: cisco.com. (107) (DF) (ttl 64, id 0, len 135)

[snip]

We can see that the DNS queries are indeed SRV records, but even without SRV records in my database, the hostname eventually resolves. I don't know how many times the phone will retry for the SRV records, but it will eventually fall back to A records, and it will resolve very quickly (no noticeable delay).

You can run into some delay problems if you're running multiple DNS servers and the first server is unresponsive. The reason it resolves so quickly in the above case is that the phone is getting a reply from the DNS server, but it's getting an NXDOMAIN reply for the SRV records, not a NOERROR reply (success), so it knows to retry. In the event of a downed DNS server, the device has a nontrivial timeout before retrying, so it will introduce delay.

Using IP addresses is easiest in our lab, only because DNS management is an additional step and usually not necessary for our purposes, but DNS is a realistic expectation in deployments. With a single DNS server, everything works great, even without the SRV records.

For redundancy, the recommendation, instead of using multiple DNS servers configured in the phone to provide redundancy, is to use some kind of load balancing device in front of your DNS cluster (i.e. Cisco CSS-11xxx) so you would provide a single DNS IP to the phone and the SLB device would handle the load balancing.

Regards,

Clay

New Member

Re: 7960 SIP in standalone mode

Thanks Clay. I suspected that would be the way the phone behaved. By the

way we use SRV records for redundancy.

Thanks,Steve

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