digits_len
return len + digits_len(ct, dptr, limit, shift);
dptr += digits_len(ct, dptr, limit, shift);
[SIP_HDR_CSEQ] = SIP_HDR("CSeq", NULL, NULL, digits_len),
[SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len),
[SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len),
[SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len),
[SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len),