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No dialtone/ringtone on M25 with M700


while dialing and waiting for the connection, I can't hear any dialtones or ringtones. Absolute silence.

After establishing the connection, we could hear each other well.

We have a M700 with one M25 registered. PBX is a Snom One 4.5

Any ideas?

Regards, Philip



beim Wählvorgang sind weder Wähltöne noch ein Rufsignal zu hören. Das ist sehr verwirrend, da nicht klar ist, ob das Telefon wählt oder nicht. Plötzlich geht der Gesprächspartner ran.

Nach dem Aufbau des Gespräches können wir normal miteinander sprechen. 

Es handelt sich um ein M25 an einer M700-Basis, die PBX ist eine Snom One 4.5

Irgendwelche Vorschläge?

Viele Grüße,


Best Answer

I've opened a support ticket


1 person has this question

Dear Philip,

could you update to our latest firmware version?



I've got the same problem with a snom m325 connected to a LANCOM 1784VA. 

In the M300's SIP log I can see that the message SIP/2.0 180 Ringing ... is being received, but I don't hear the ringtone on the handset.

After having this problem with FW 324 I updated to 355, no change so far.

Any ideas how to solve this problem?




I've opened a support ticket


The problem still exists. Do you have any suggestions by now?

Dear Igor,

please try to use different codec and verify if the issue is still present.

If Yes, please open a support ticket. We'll look deeper into it.


same problem , did you find a solution


Dear Helmut,

in a lot of this cases the M700 doesn't receive the 180 ringing from the pbx.

You need to setup the trunk in order to send the Ringback in early media.


Sorry can you explain waht means doesn't receive the 180 ringing from the pbx


180 Ringing is a SIP message (see

Does the issue happens only calling external numbers (so trough a SIP trunk) or also calling other PBX extensions ?


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