Cisco Support Community
Community Member

Incoming fax issue connected to VG224


We have fax connected to Vg 224(IOS 12.4(9)T6 which inturn is registered with CCM 4.2(3)sr2b.

Outgoing fax works fine but we have issues in receiving fax.

For incoming,Caller hear a fax tone and also we see "receiving Page 1" on fax machine but finally get an error message "..Error Please ask the sender to send again" on the fax machine after some time without receiving any fax.Caller sees a communication error on his Fax.

This is happening in all Vg 224 running different IOS versions.

Any configuration to be done on VG224?




Cisco Employee

Re: Incoming fax issue connected to VG224

Based on ths description, the VG224 is sounds like it is OK - the problem is with the fax traffic getting from your main gateway to the VG224, it is not an issue with traffic from the VG224 towards the main gateway.

Most common reason this happens - clock slips on the PSTN gateway digital trunks.

Assuming you have some kind of T1/E1 gateway, do a show controller and check the stats - if you see clock slips then this could be the problem.

The reason why the faxes work VG224 ---> PSTN is the traffic in this direction does not experience slips, but the traffic PSTN ---> VG224 has slips in the bit stream, which cause errors in the data, the fax protocols detect these erorrs and retransmit, but the errors keep occuring and eventually the fax machine drops the call.

Assuming you have a T1 card in slot 0/0/0 of the PSTN gateway router, you need the following commands -

network-clock-participate t1 wic 0

network-clock-select 1 t1 0/0/0

this will recover the clock signal off the PRI on controller e1 0/0/0 and use it to drive the DSP's and the traffic in the TX direction, so there will be a common clock reference system wide and the slips should be cleared.

If this does not help, then tell us more about the setup of the entire network and how it interfaces to the PSTN.

Community Member

Re: Incoming fax issue connected to VG224

Thanks for replying.The above commands are already there on the gateway.

We have ccm 4.2(3)sr2b setup to which VG 224 is registered through SCCP and the local PSTN Gw(2851 rtr with E1 PRI) is registered trough MGCP. The fax is connected to the VG 224.

Outgoing fax is fine,the problem is only with incoming.



Cisco Employee

Re: Incoming fax issue connected to VG224

please post SH RUN and SH VER from the 2851 and VG224 - I need to see how they have been set up.

Community Member

Re: Incoming fax issue connected to VG224

Dear Pcameron

i have same probelm, but i user CCM v6.0

please help me too.


Re: Incoming fax issue connected to VG224

Do a Show network-clocks to confirm you are clcoking of the line also if you are using MGCP what is the clock source in CCM, CUCM again make sure it is external

CreatePlease to create content