ast*CLI> show translation 
         Translation times between formats (in milliseconds)
          Source Format (Rows) Destination Format(Columns)

         g723   gsm  ulaw  alaw  g726 adpcm  slin lpc10  g729 speex  ilbc
   g723     -     -     -     -     -     -     -     -     -     -     -
    gsm     -     -     4     4    11     4     3    13    38     -    52
   ulaw     -    10     -     1     9     2     1    11    36     -    50
   alaw     -    10     1     -     9     2     1    11    36     -    50
   g726     -    16     8     8     -     8     7    17    42     -    56
  adpcm     -    10     2     2     9     -     1    11    36     -    50
   slin     -     9     1     1     8     1     -    10    35     -    49
  lpc10     -    17     9     9    16     9     8     -    43     -    57
   g729     -    16     8     8    15     8     7    17     -     -    56
  speex     -     -     -     -     -     -     -     -     -     -     -
   ilbc     -    18    10    10    17    10     9    19    44     -     -
ast*CLI> 


show modules output
codec_g729a.so            Annex A/B (floating point) G.729 Codec ( 0       

when i m calling from both lines of linksys pap2. one line works and other gives me error on console of asterisk. here is the output.
Nov  9 16:35:03 NOTICE[1589]: res_musiconhold.c:309 monmp3thread: Request to schedule in the past?!?!
Nov  9 16:38:03 NOTICE[1589]: res_musiconhold.c:309 monmp3thread: Request to schedule in the past?!?!
    -- Executing Dial("SIP/ast.d2visp.com-0814b270", "SIP/18158340674@isphone|30") in new stack
    -- Called 18158340674@isphone
    -- SIP/isphone-ee39 is making progress passing it to SIP/ast.d2visp.com-0814b270
    -- SIP/isphone-ee39 is ringing
Nov  9 16:40:13 NOTICE[1589]: chan_sip.c:2792 process_sdp: No compatible codecs!
Nov  9 16:40:15 NOTICE[1589]: rtp.c:298 process_rfc3389: RFC3389 support incomplete.  Turn off on client if possible
    -- SIP/isphone-ee39 answered SIP/ast.d2visp.com-0814b270
    -- Attempting native bridge of SIP/ast.d2visp.com-0814b270 and SIP/isphone-ee39
  == Spawn extension (ser-in, 18158340674, 1) exited non-zero on 'SIP/ast.d2visp.com-0814b270'