[Serusers] xten and Mitel 5055

Hi, apologies for using this email list for something which is not directly linked to ser. I'm having a weird problem when setting up a voice connection between an Xten X-Lite UA and a Mitel 5055 SIP phone (connected via a ser proxy server). The session initiation is all fine, but the media session is not - the voice transmitted sounds a bit like a robot and is impossible to understand. I assumed this is a codec problem but strangly this problem ONLY occurs between the Xten UA and the Mitel phone. It does not occur between Xten and a Pingtel phone nor between Mitel 5055 and Pingtel, nor between Ubiquity UA and Mitel 5055. As far as I know all use the G711 codec. Has anybody experienced this problem also? Thank you for your help. Mario Kolberg -- The University of Stirling is a university established in Scotland by charter at Stirling, FK9 4LA. Privileged/Confidential Information may be contained in this message. If you are not the addressee indicated in this message (or responsible for delivery of the message to such person), you may not disclose, copy or deliver this message to anyone and any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. In such case, you should destroy this message and kindly notify the sender by reply email. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind.