Section: 5.2.1.12 Cellular Text telephone Modem (CTM) selection
Content: The mobile station can send a CTM support indication in the Bearer Capability IE in call establishment messages to inform the network of the use of CTM text in the call. When the mobile station indicates speech and support of CTM text telephony, the network shall select a speech codec and additionally CTM text telephony detection/conversion functions as specified in 3GPP TS 23.226[ Global text telephony (GTT); Stage 2 ]  [92] and 3GPP TS 26.226[ Cellular text telephone modem; General description ]  [93], if such functions are available. NOTE: If CTM support is indicated by the mobile station, then it supports CTM text telephony together with any supported speech codec and for any supported radio access.