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Astra 6731i cannot register U1981

Publication Date:  2017-01-20 Views:  79 Downloads:  0
Issue Description

We have an IP PBX Huawei U1981 and cannot register to it an Astra IP Phone 6731i, but a Polycom IP Phone is registering without any technicl difficulties.

When Astra IP Phone is tring to register to the U1981 PBX, the PBX is returning a "403 Forbidden" SIP error message to the REGISTER packet.

Alarm Information

When Astra IP Phone is tring to register to the U1981 PBX, the PBX is returning a "403 Forbidden" SIP error message to the REGISTER packet.

Handling Process

I captured network packets for both Astra and Polycom IP Phones to make a comparison on their Register packets so i can observe the differences.

Root Cause
In the below image we can see the Register packets, in the left for Astra phone and in the right side the packet from the Polycom phone.

Astra's 403 Forbidden response:



Polycom's 200 OK response:





From the above we have identified two abnormal lines in Astra's registering packet:

1. Astra IP Phone has the same user ID/calling ID "2002", the same as the Polycom IP Phone, which is leading to a conflict registration for Astra
2. Astra's registering packet does not contain any "Expires: xxxx" line in order to know at which interval should renew the registration with the registrar server
Solution
Because i identify two problems in Astra's register packet i resolved them in the following order:

First, I have changed the user ID/calling ID from "2002" into "2003" in order to get rid of the conflict with the Polycom phone



After this change was saved, i have restarted the Astra phone and made a SIP trace directly into the U1981's CLI interface and also captured Polycom's register packet.

The output was the below:

POLYCOM Register packet:

REGISTER sip:IP Address:5060;transport=tcp SIP/2.0
Via: SIP/2.0/TCP IP Address;branch=z9hG4bK71cb0c6b69F4C9E
From: "2002" <sip:2002@IP Address>;tag=6F93312D-1897D830
To: <sip:2002@IP Address>
CSeq: 1 REGISTER
Call-ID: 643f9589-460a91ec-13594a87@IP Address
Contact: <sip:2002@IP Address;transport=tcp>;methods="INVITE, ACK, BYE, CANCEL, OPTIONS, INFO, MESSAGE, SUBSCRIBE, NOTIFY, PRACK, UPDATE, REFER"
User-Agent: PolycomSoundPointIP-SPIP_320-UA/3.3.3.0069
Accept-Language: es-es,es;q=0.9,en;q=0.8
Max-Forwards: 70
Expires: 3600
Content-Length: 0

.
SIP/2.0 200 OK
Via: SIP/2.0/TCP IP Address;branch=z9hG4bK71cb0c6b69F4C9E
Call-ID: 643f9589-460a91ec-13594a87@IP Address
From: "2002"<sip:2002@IP Address>;tag=6F93312D-1897D830
To: <sip:2002@IP Address>;tag=amgavdws
CSeq: 1 REGISTER
Contact: <sip:2002@IP Address:5060>;expires=3600
Expires: 3600
Server: eSpace U1981/V200R003C20SPC300B015
Content-Length: 0


ASTRA Register packet:

REGISTER sip:IP Address:5060 SIP/2.0
Via: SIP/2.0/TCP IP Address:5060;branch=z9hG4bK45a9929be07c0ba21
Max-Forwards: 70
From: "2003" <sip:2003@IP Address:5060>;tag=e3f3473660
To: "2003" <sip:2003@IP Address:5060>
Call-ID: 1baf0d32cf961815
CSeq: 10938 REGISTER
Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, OPTIONS, UPDATE, PRACK, SUBSCRIBE, INFO
Allow-Events: aastra-xml, talk, hold, conference, LocalModeStatus
Contact: "2003" <sip:2003@IP Address:5060;transport=tcp>;+sip.instance="<urn:uuid:00000000-0000-1000-8000-00085D341FDA>"
Supported: path, gruu
User-Agent: Aastra 6731i/3.3.1.2234
Aastra-Line: 1
Content-Length: 0

.
SIP/2.0 400 Bad Request
Via: SIP/2.0/TCP IP Address:5060;branch=z9hG4bK45a9929be07c0ba21
Call-ID: 1baf0d32cf961815
From: "2003"<sip:2003@IP Address:5060>;tag=e3f3473660
To: "2003"<sip:2003@IP Address:5060>;tag=fxax5yw4
CSeq: 10938 REGISTER
Server: eSpace U1981/V200R003C20SPC300B015
Content-Length: 0


According to the above logs, we can see that the Astra's caller ID has been changed, and the response has changed from "403 Forbidden" into "400 Bad Request"

Now we ran into the second problem i have observed initially: the lack of the "Expires: 3600" field which is missing in the Astra's REGISTER packet as per above trace.

The solution was to implement the "Expires" line into the Astra Phone from it's web interface as per below:



After this change the registration problem of the Astra phone was resovled, as per below SIP trace:

REGISTER sip:IP Address:5060 SIP/2.0
Via: SIP/2.0/TCP IP Address:5060;branch=z9hG4bK45a9929be07c0ba21
Max-Forwards: 70
From: "2003" <sip:2003@IP Address:5060>;tag=e3f3473660
To: "2003" <sip:2003@IP Address:5060>
Call-ID: 1baf0d32cf961815
CSeq: 10938 REGISTER
Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, OPTIONS, UPDATE, PRACK, SUBSCRIBE, INFO
Allow-Events: aastra-xml, talk, hold, conference, LocalModeStatus
Contact: "2003" <sip:2003@IP Address:5060;transport=tcp>;+sip.instance="<urn:uuid:00000000-0000-1000-8000-00085D341FDA>"
Supported: path, gruu
User-Agent: Aastra 6731i/3.3.1.2234
Aastra-Line: 1
Expires: 3600
Content-Length: 0

.
SIP/2.0 200 OK
Via: SIP/2.0/TCP IP Address:5060;branch=z9hG4bK45a9929be07c0ba21
Call-ID: 1baf0d32cf961815
From: "2003"<sip:2003@IP Address:5060>;tag=e3f3473660
To: "2003"<sip:2003@IP Address:5060>;tag=fxax5yw4
CSeq: 10938 REGISTER
Contact: <sip:2003@IP Address:5060>;expires=3600
Expires: 3600
Content-Length: 0
Suggestions

As a suggestion, you need to be very carefull about configuration of the IP Phones and to pay attention about what other IP Phones you have in the LAN to avoid the conflicts.

END