RTP Map different from providers

Hello, Using 1.2.9.1 asterisk compiled from source on Redhat ES 4.0
Call comes from provider who send an audio list like:

media Description, name and address (m): audio 39308 RTP/AVP 103 102 18 97 100 0 8 117 13 101
Media Type: audio
Media Port: 39308
Media Proto: RTP/AVP
Media Format: 103
Media Format: 102 <<-- here is iLBC
Media Format: ITU-T G.729
Media Format: 97
Media Format: 100
Media Format: ITU-T G.711 PCMU
Media Format: ITU-T G.711 PCMA
Media Format: 117
Media Format: Comfort noise
Media Format: 101

Asterisk completes the call, but sends back iLBC as PT 97:

        Media Description, name and address (m): audio 18870 RTP/AVP 97 0 101
            Media Type: audio
            Media Port: 18870
            Media Proto: RTP/AVP
            Media Format: 97
            Media Format: ITU-T G.711 PCMU
            Media Format: 101
        Media Attribute (a): rtpmap:97 iLBC/8000
            Media Attribute Fieldname: rtpmap
            Media Attribute Value: 97 iLBC/8000

My provider seems to be unable to deal with this. How can I reconfigure asterisk to use PT 102 for iLBC? (I only care about iLBC and g711u law on this server.)

Thanks in advance.