I've been working at this one for a while with Mitel support to no avail, not sure if anybody's had something similar. Users at a specific site (running over an ADSL / PPPoE connection) have issues when transferring calls, or retrieving them from hold. This site is able to route directly to the MiVB and SIP server so no teleworker in use currently.
If they attempt to transfer a call, then press 'Back to Held' to return to the call, the caller will remain stuck on hold even though the call appears active on their screen. They then cannot reconnect to the call at all, however the call will end if they hang up the handset.
A similar thing will happen if they go through with the transfer by pressing the 'Transfer' button on their phone, except the call just gets stuck on the destination phone instead. If they process the transfer by hanging up the handset instead of pressing 'Transfer', the call will go through successfully and the destination phone is connected to the caller.
The call will get stuck even if they put it on hold and then attempt to take it off hold normally.
The above issues all occur 90% of the time, however it sometimes will work.
This issue only seems to occur over PPPoE connections, so I'm wondering if it may be MTU related due to the extra overhead on packets. Is there a way to reduce the MTU on the Mitel handsets themselves?
Any help would be appreciated.
Thanks.
